Biofuel Composition and Method of Producing a Biofuel

ABSTRACT

An emulsified biofuel composition comprising: (A) a continuous phase comprising about 50-95 wt % of at least one liquid oil of vegetable or animal origin or mixtures thereof; (B) a water-containing dispersed phase comprising about 1-50 wt % water; (C) about 1-25 wt % of hydroxyl-containing organic compound selected from the group consisting of mono-, di-, tri- and polyhydric alcohols, provided that when a monohydric alcohol is used there is also present at least one of tert-butyl alcohol, at least one C2-C4 alkylene glycol or a mixture of both; (D) about 0.05-10 wt % of at least one emulsifier; wherein the dispersed water-containing droplets have an average particle size of less than about 20 microns. The biofuel is prepared from these components by mixing under high shear conditions, preferably with ultrasonic energy. The emulsifier(s) preferably exhibit a hydrophilic-lipophilic balance of about 8.5 to about 18 and the biofuel includes a cetane enhancer and mixture of an alcohol and mono- or poly-alkylene glycol.

CROSS REFERENCE

The present application claims the benefit of Application Ser. No.60/795,365, filed Apr. 27, 2006, entitled Biofuel Additive and Method ofProducing a Biofuel, the disclosure of which is hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to fuel additives, methods of making suchadditives and fuel compositions employing such additives, wherein thefuel is substantially based on vegetable or animal sources.

Efforts to find alternative fuels to those derived from petroleum, suchas gasoline and diesel fuel, have led to the development of biodieselfuel. Traditional biodiesel is produced by transesterification ofvegetable oils or fats. In such a process, a vegetable fat or oil reactswith an esterifying agent, typically an alcohol, for example methanol orethanol, with or without a catalyst and with the input of additionalenergy usually at atmospheric pressure. The time of the reaction canrange from 0.5 to 8 hours depending on the temperature.

The terms “oils” and “fats” are often considered synonyms, and for thepurposes of the present application can be considered chemicallyinterchangeable, the distinction between such products being that theyare merely distinguished on the basis of their physical state. Forexample, an “oil” is typically used to describe products that are liquidat ambient or room temperature whereas the term “fat” is used todescribe products that are typically substantially solid at roomtemperature. However, even such a differentiation is somewhat artificialin that it is subject to the definition of room temperature. Forexample, the same product may be considered a “fat” in one latitude at agiven time of the year and be considered an “oil” at another latitude orat another time of the year. To avoid confusion with other types of oils(such as essential oils or oils derived from petroleum), these productswill be identified to the extent possible as “vegetable or animal oils”or “vegetable or animal fats” but unless the context clearly indicatesotherwise, a reference to fats and oils should be understood to refer tovegetable or animal oil components useful in the present invention, asopposed to, e.g., petroleum oils. In other words, if an oil obtainedfrom petroleum, such as diesel oil, gas oil and the like, is present inthe compositions of the present invention at all, it is present as anadditive or minor component, in other words, in an amount less than 50wt %; for example, less than about 40, 30, 20, 10, 5 or even 3 wt %;such as from greater than about 0 wt % to less than about 5 wt %, or 10wt %, or 15 wt % or 20 wt %, or 25 wt %.

A common vegetable-oil-derived fuel, typically used as a fuel for dieselengines is referred to as “biodiesel.” Biodiesel is made utilizing thechemical reaction known as transesterification. The process forms twoprincipal products, fatty acid methyl esters (FAME, the chemical namefor biodiesel) and glycerin. In this reaction a vegetable oil or fatreacts with an esterifying agent, usually an alcohol (e.g., methanol orethanol), with or without a catalyst and with the input of additionalenergy, normally at atmospheric pressure. The reaction time can varyfrom about 0.5 to about 8 hours depending on the temperature and whetheror not a catalyst is used. A biodiesel fuel generated in this way andused in its pure form (in other words without being “diluted” withanother fuel, whether a petroleum based fuel or ethanol) at 100% isreferred to as “B 100”. If it is diluted with another fuel, e.g., dieselfuel or gas oil, it is typically identified by the percentage ofbiodiesel present, e.g., B5, B20, B30, etc. The principal physical andchemical properties of traditional biodiesel are as follows: methylester content >96.5%; Density at 15° C. ranges from about 0.86 to about0.90 g/cc; viscosity at 40° C. between about 3.5 and about 5.0 mm²/s;flammability point >110° C.; Cetane number >51; net heating value equalto about 33175 kJ/L (compared to typical No. 2 diesel fuel, biodieselhas about 8.65% less heating value expressed as BTU/gal.; i.e., 118,296versus 129,500).

Furthermore, traditional biodiesel fuel exhibits a distillation curvethat is different from traditional gas oil. This results in a flameprofile that is longer and more compact because of the greater viscosityand density of biodiesel compared to petroleum-based diesel fuel. Such aflame can create operational problems if the pressure of the volumetricfuel pump is not increased slightly, e.g., about 1-1.5 atm. For the samereason, modified fuel nozzles having a form more suited to thecharacteristics of biodiesel need to be used; for example, 60° nozzlesopen at the center perform best.

In addition, the use of biodiesel requires further adjustments of therelationship of primary air to secondary air (regulation of thecombustion head). However, this introduces further complications sinceincreasing secondary air improves cold performance of the engine, butslightly worsens equilibrium combustion and vice versa. Anotherdisadvantage of traditional biodiesel arises from the high solvent powerof methyl ester. This can cause damage to incompatible plastics,generally present as liners and seals, and may also create problems withdeposits of gas oil inadvertently left in the storage tanks. Therefore,substitution for, or at least the periodic maintenance of the polymericcomponents, is also required (including, for example, the intake andreturn tubes, the compression seals of the pump, the bending elements,and the liners and seals). Furthermore, the cleaning of tanks andheaters in order to remove all residues of fossil fuels is also stronglyadvised.

Traditional biodiesel mixed with lubricating oil may also create avariety of problems because of the increase in the iodine number of themixture; iodine number being an indicator of organic unsaturation. Ifthe iodine number of the oil is greater than about 115, the mixture issusceptible to polymerization, and gummy deposits can form in thelubrication lines, reducing the flow of the lubricant. This can resultin an undesirable need to replace the motor's lubricant oil. Inaddition, because the composition of biodiesel is very different fromgas oil, its behavior in terms of exhaust emissions sometimes markedlyvaries from that of gas oil, particularly NOx emissions.

When traditional biodiesel is used in an engine with fuel injectors,deposits tend to form in the injectors, at least two to three times moreso than when gas oil is used. Such deposits are usually carbon depositsand tend to wear away with time, particularly in “common rail” typemotors. However, deposit problems can be avoided with traditionalbiodiesel fuel if the injection pressure is increased, e.g., to about100 bar.

Methanol used in the transesterification process results in a minimaladdition of fossil-based CO₂ in the balance of traditional biodiesel. Ifthe source of oil used to produce the biodiesel is derived fromrenewable sources (typically referred to as biomass), then all of theCO₂ produced by the combustion of the biodiesel is renewable. However,the problem of nitrogen oxides, currently considered among the mostundesirable by-products of combustion, is the weak point of traditionalbiodiesel fuel. On average NOx emissions increase 10-13% with respect togas oil on account of the high oxygen content of the biofuel. Even mixescontaining less than 100 biodiesel cause an increase in NOx emissions.For example, for B20, the increase is around a 2-3% over gas oil. On theother hand, CO emissions for B100 are on average about 40% less than forgas oil whereas a B20 biodiesel mixture emits around 15% less CO. Carbonmonoxide in the motor area does not generate significant problems andcan be considered a lesser pollutant. It is rather an indicator of poorcombustion since it is the result of a lack of oxygen.

Particulate emissions from the burning of biodiesel may be related tothe chemical composition of the source used to synthesize the biodieseland also may be indicative of combustion-related problems. The dangerassociated with such particulates varies with their chemical compositionand to the average dimension of the particles. Additionally, theparticles can also absorb and/or adsorb a certain amount of aromaticsubstances that are considered more or less carcinogenic and/ormutagenic. SO₂ emission can be a problem if the biodiesel is notentirely devoid of sulfur. Obviously the mixture of gas oil andbiodiesel leads to an increase in emissions of SO₂ that is proportionateto the content of fossil fuel. The use of traditional biofuel in boilershas not yet been the subject of in-depth study. For example, themeasured quantity of particulate emissions, NOx, SO₂ and CO, from thestack of a 1750 kWatt boiler fed with biodiesel compared with thoseemitted from one that burns gas oil containing 0.25 wt % sulfur showthat the pollutants emitted by biodiesel are less than those of gasoil-with the exception of NOx, which is higher.

Finally, on the basis of raw materials costs, biodiesel is significantlymore expensive, for example, as currently calculated based on Europeancosts, than regular diesel fuel. Final costs “at the pump” can beequivalent since there currently are government incentives to encouragethe use of a non-petroleum-based fuel.

Thus, further improvements in the field of non-petroleum based fuels,especially fuels based on renewable vegetable sources would be highlydesirable, particularly where such fuels exhibit acceptable performancecharacteristics.

SUMMARY OF THE INVENTION

In one embodiment an emulsified biofuel composition suitable for use indiesel engines comprises: (A) a continuous phase comprising about 50-95wt % of at least one liquid oil of vegetable or animal origin ormixtures thereof; (B) a water-containing dispersed phase comprisingabout 1-50 wt % water; (C) about 1-25 wt % of hydroxyl-containingorganic compound selected from the group consisting of mono-, di-, tri-and polyhydric alcohols, provided that when a monohydric alcohol is usedthere is also present at least one of tert-butyl alcohol, at least oneC2-C4 alkylene glycol or a mixture of both; (D) about 0.05-10 wt % of atleast one emulsifier; wherein the dispersed water-containing dropletshave an average particle size of less than about 20 microns. The biofuelis prepared from these components by mixing under high shear conditions,preferably with ultrasonic energy. The at least one emulsifierpreferably exhibits a hydrophilic-lipophilic balance of about 8.5 toabout 18 and the biofuel includes a cetane enhancer and mixture of analcohol and mono- or poly-alkylene glycol.

In one embodiment the dispersed aqueous phase in an emulsified fuelcomprising a vegetable oil continuous phase exhibits an average dropletparticle size of about 0.01 to about 15 microns and the emulsifier(s)exhibit a hydrophilic-lipophilic balance, HLB, of about 8.5 to about 18.

In another embodiment an emulsified fuel mixture is prepared from thefollowing components: (A) vegetable or animal oil or fat, includingmixtures thereof; and B) water; and (C) at least one alcohol selectedfrom the group consisting of C1 to C4 alcohols; and, (D) at least onesurfactant or emulsifier and optionally a supplementary low viscosity,low density combustible liquid selected from the group consisting ofhydrocarbon solvents, paint thinner, turpentine, mineral spirits andmixtures thereof. In one embodiment, the latter emulsified fuel mixturecan be prepared according to the following method: (I) components (C)and (D) are mixed with one another to produce an additive and theadditive is combined with water (B) to form mixture (II). Mixture (II)is added with concurrent mixing, at a suitable rate to the vegetableoil, component (A), in order to produce a substantially emulsifiedmixture.

DETAILED DESCRIPTION

As used herein the following terms or phrases have the indicatedmeanings.

The term “emulsion” refers to a mixture or dispersion of two immisciblesubstances, liquids in the present invention, in which one substance,the dispersed phase, is dispersed in the other substance, the continuousphase. An emulsion is stabilized, in other words the dispersed phaseremains dispersed during the relevant time period, such as duringstorage and/or immediately prior to and during use, with the assistanceof one or more substances known as emulsifiers. An emulsion can be awater-in-oil emulsion or an oil-in-water emulsion depending on suchvariables as the amount of oil (as well as type of oil) and waterpresent, the conditions used to prepare the emulsion, the emulsifiertype and amount, the temperature and combinations of such variables. Theparticle size or droplet size of the dispersed phase can vary over asignificant range and the emulsion can remain stable, but its propertiesand suitability for a specific use may vary depending on the particlesize of the dispersed phase. Particle size is typically expressed interms of mean or average size since the uniformity of the dispersedphase can also vary depending on the variables noted above. Particlesize does not require that the particles are necessarily spheres and thesize of the particles can be based on a major or average dimension ofeach particle, although in a system comprising a dispersed liquid phasein a continuous liquid phase, fluid dynamics suggest that the dispersedparticles will tend to be substantially spherical.

The term “emulsifier” refers to a compound or mixture of compounds thathas the capacity to promote formation of an emulsion and/orsubstantially stabilize an emulsion, at least for the short-term, i.e.,during the time of practical or commercial interest. An emulsifierprovides stability against significant or substantial aggregation orcoalescence of the dispersed phase of an emulsion. An emulsifier istypically considered to be a surface active substance in that it iscapable of interacting with the dispersed and continuous phases of anemulsion at the interface between the two. For purposes herein a“surfactant” and an “emulsifier” are considered equivalent orinterchangeable terms. Furthermore, within the generic term surfactantare included the various types of surfactants such as nonionic, ionic orpartially ionic, anionic, amphoteric, cationic and zwitterionicsurfactants.

The term “cetane number” refers to a measure of diesel fuel ignitioncharacteristics which is analogous to octane number for gasoline and,similarly, higher values indicate better performance. A specific testhas been developed and accepted by the fuel industry and it is defined,for example, by various standards setting organizations including ASTMD613, IP 41, and EN ISO 5165. The test method determines the rating ofdiesel fuel oil in terms of an arbitrary scale of cetane numbers using astandard single cylinder, four-stroke cycle, variable compression ratio,indirect injected diesel engine. The cetane number scale covers therange from zero to 100 but typical test results for diesel fuel andfuels intended for use in diesel applications are typically in the rangeof 30 to 65 cetane number.

The term “flash point” generally refers to how easily a substance orcomposition, typically a fluid, may ignite or burn. The measurement offlash point is defined in test methods that are maintained bystandardization bodies such as the Energy Institute in the UK, ASTM inthe USA, CEN in Europe and ISO internationally. For example, for dieselfuel the procedure is defined in ASTM D975. The flash point of a fuel isessentially the lowest temperature at which vapors from a test portioncombine with air to give a flammable mixture and “flash” when anignition source is applied. Materials with higher flash points are lesslikely to ignite than those with lower flash points. For example, aflash point of 66° C. to 93° C. (150° F. to 200° F.) is considered topresent a moderately low ignition hazard and a flash point of 38° C. to66° C. (100° F. to 150° F.) is considered to present a moderate to highignition hazard. For reference purposes diesel fuel has a flash point ofabout 38° C. to 54° C. (100° F.-130° F.) and gasoline a flash point ofabout −40° C. to −46° C. (−40° F. to −50° F.). The flash point of a fuelis one property that needs to be considered in determining thesuitability of a fuel composition for practical use.

The term “mixing” when used generically or without a modifier includeseach of the processes described herein for dispersing one ingredient inanother.

The term “hydrocarbyl substituent” or “hydrocarbyl group” is used in itsordinary sense, which is well known to those skilled in the art.Specifically, it refers to a group having a carbon atom directlyattached to the remainder of the molecule and having predominantlyhydrocarbon character. Examples of hydrocarbyl groups include: (1)hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-,aliphatic-, and alicyclic-substituted aromatic substituents, as well ascyclic substituents wherein the ring is completed through anotherportion of the molecule (e.g., two substituents together form analicyclic radical); (2) substituted hydrocarbon substituents, that is,substituents containing non-hydrocarbon groups which, in the context ofthis invention, do not alter the predominantly hydrocarbon substituent(e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto,alkylmercapto, nitro, nitroso, and sulfoxy); (3) hetero substituents,that is, substituents which, while having a predominantly hydrocarboncharacter, in the context of this invention, contain other than carbonin a ring or chain otherwise composed of carbon atoms. Heteroatomsinclude sulfur, oxygen, nitrogen, and encompass substituents as pyridyl,furyl, thienyl and imidazolyl. In general, no more than two, preferablyno more than one, non-hydrocarbon substituent will be present for everyten carbon atoms in the hydrocarbyl group; typically, there will be nonon-hydrocarbon substituents in the hydrocarbyl group.

The term “lower” when used in conjunction with terms such as alkyl,alkenyl, and alkoxy, is intended to describe such groups that contain atotal of up to 7 carbon atoms.

Reference in the disclosures that follow to “oil” in general refers tovegetable oils, animal derived oils and mixtures of vegetable and animalderived oils, including recycled versions thereof. Unless the context ofthe description requires otherwise, reference to “vegetable oil” shouldbe understood to include a reference to animal derived oils and mixturesof both vegetable and animal derived oils.

The terms “stability” or “stable” when used in reference to an emulsionrefer to the dispersed or hydrophilic phase remaining substantiallydispersed in the lipophilic phase (vegetable and/or animal oil and/orfat). In other words, substantially no phase separation occurs asindicated by visual observation after a period following preparation ofthe emulsion of at least about 24 hours; preferably at least about 48hours, more preferably at least about 72 hours; for example,substantially no phase separation is observable after about 4 days ormore, at ambient temperatures suitable for use of the emulsified fuelcomposition in its directed application, for example, use in burners,motor vehicles and the like. Alternatively, stability can becharacterized by measuring sediment formation according to the testmethod ASTM D96.

Compositions of the present invention, characterized for purposes of thepresent invention as fuel compositions, and referred to as “biofuel,”are suitable for use in internal combustion engines, preferably dieselengines of various configurations as well as in equipment that combustsfuels to generate heat, such as furnaces, boilers, power generatingequipment and the like, including gas or combustion turbines. Dieselengines that may be operated with compositions of the present inventioninclude all compression-ignition engines for both mobile (includinglocomotive and marine) and stationary power plants. These include dieselengines of the two-stroke-per-cycle and four-stroke-per-cycle types. Thediesel engines include but are not limited to light and heavy dutydiesel engines and on and off-highway engines, including new engines aswell as in-use engines. The diesel engines include those used inautomobiles, trucks, buses including urban buses, locomotives,stationary generators, and the like. For example, with regard to use inburners, the compositions are useful in different types of oil burnersfor domestic and other heating purposes including sleeve burners,natural-draft pot burners, force-draft pot burners, rotary wall flameburners, and air-atomizing and pressure-atomizing gun burners; with thelatter type of burner being the most commonly used burner for homeheating, particularly in the United States. In particular, suchcompositions are useful fuels for diesel motors (both new and oldgeneration) and/or boilers and single- or multi-step burners, alsoreferred to in the art as staged burners.

Various mixing devices well known in the art can be employed tofacilitate formation of an emulsified composition of the instantembodiment as well as the present invention generally including, forexample, mixer-emulsifiers, which typically utilize a high speed rotoroperating in close proximity to a stator (such as a type made by CharlesRoss & Sons Co., NY), paddle mixers utilizing paddles having variousdesign configurations including, for example, reverse pitch, anchor,leaf, gate, finger, double-motion, helix, etc., including batch andin-line equipment, and the like. Other methods of mixing useful in thisembodiment as well as generally in the present invention are furtherdescribed hereinbelow. The processes of various embodiments of thepresent invention can be carried out at a convenient temperature,including, for example, at ambient or room temperature, such as about20° C. to about 22° C. or even as high as 25° C. The time andtemperature of mixing can be varied provided that the desired emulsifiedcomposition is achieved and, based on subsequent observation and/ortesting, it is suitably stable until it is used, as well as during use.Under conditions wherein sediment may form following mixing of thecomponents of the fuel composition, it can be desirable to wait for aperiod of time in order to allow for sedimentation, if any, to occur,such material to subsequently be removed or separated from theemulsified fuel composition. Typically, such time period is at leastabout 4 minutes; preferably about 5 minutes; more preferably about 6minutes or more. The preferred amount of time can readily be determinedwith limited and simple experiments and such time can be adjusted, basedon, for example, the type, quality and composition of the vegetable oilemployed, as well as the other components of the mixture, includingemulsifier(s).

Mixing methods in additions to those described above are suitable foruse in the present invention and in some instances are particularlypreferred. Mixtures can be prepared with traditional mixing or blendingequipment such as vats or tank equipped with motor driven stirrershaving various configurations, e.g., paddle, helix, etc. Mixing carriedout in such equipment is time consuming, often requiring greater than 10minutes of mixing, for example, about 10 to about 30 minutes,alternately about 15 to about 20 minutes in order to achieve a uniformand stable emulsion. However, such emulsions contain dispersed particleshaving an average particle size, e.g., diameter or average dimension onthe order of greater than about 20 microns; for example, about 20 toabout 50 microns; alternatively about 20 to about 35 microns. Emulsionshaving an average particle size of about 20 microns or greater arereferred to herein as “macroemulsions.” A fuel composition havingmacroemulsion characteristics will typically exhibit properties thatdiffer from the same fuel composition having an average particle sizethat is significantly smaller, in other words, a microemulsion or one inwhich the particle size is less than about 20 microns, such as 19microns or less. For example, a given composition in macroemulsion formmay exhibit a higher viscosity, lower flash point and poorer stabilityin a process requiring extended recirculation of the fuel composition aswell as requiring a greater amount of emulsifier in order to produce asatisfactory and stable emulsion compared to the same composition inmicroemulsion form.

In a preferred method, fuel mixtures of the present invention areprepared using ultrasonic mixing equipment, which equipment isparticularly advantageous for preparing stable emulsions having a smallparticle size, for example less than about 10 microns, or about 0.01 toabout 5 microns on average, in other words embodiments of amicroemulsion. Preferred equipment of this type is availablecommercially as “Sonolator” ultrasonic homogenizing system, Sonic Corp.,Conn. Such microemulsions can be prepared at ambient temperature, forexample about 22° C., and at pressures of about 500 psi to about 1500psi, although pressures as high as 5000 psi can also be used to producestable microemulsions. The Sonolator system is particularly useful inthat it can be operated in alternative, useful modes, includingsemi-continuous, continuous, single-feed or multiple-feed. Inparticular, such a system operated in multiple-feed mode can utilizefeed tanks containing, for example, vegetable oil, water, emulsifier andother components, such as alcohol, cetane enhancer, alkyl glycol oralkyl glycol derivative, etc. Such a system allows feeding of one ormore of the components simultaneously, sequentially or intermittently inorder to achieve a particularly desirable result, including but notlimited to a specific emulsion particle size, particle sizedistribution, mixing time, etc. As noted above, fuel compositionsprepared using ultrasonic emulsification can be accomplished using alower concentration of emulsifier for the same concentration of othercomponents, particularly the vegetable oil(s) and water. For example,where a composition prepared without ultrasonic mixing requires about1.0 wt % emulsifier to obtain a satisfactory emulsion, it may onlyrequire less than about 0.5 wt % emulsifier with the same composition inorder to obtain a satisfactory emulsion, preferably an enhanced emulsionin that the particle size is smaller, resulting in a microemulsion.Typically the amount of emulsifier is about 10% less than would berequired in the absence of ultrasonic emulsification; preferably about20% less; more preferably about 30% less; still more preferably about40% less; for example, about 50%, 60%, 70%, 60% or even 90% less thanthe amount of emulsifier required for a satisfactory emulsion withoutthe use of ultrasonic energy input. For example, an emulsified fuelcomposition requiring 1 wt % emulsifier to obtain an average emulsionparticle size of about 20 microns can be replaced with 0.2 wt % of thesame emulsifier in the same composition to obtain an emulsion having aparticle size of about 5 microns. For purposes herein, the use of adevice that introduces ultrasonic energy for mixing and emulsificationis referred to as a “high shear” method, regardless of the physicalprocesses that may occur on a microscopic or molecular scale.

Emulsification using high shear such as imparted by an ultrasonic deviceresults in an emulsion having a mean particle or droplet size in therange of about 0.01 microns to less than about 20 microns; such as about0.01 microns to about 15 microns; or about 0.1 microns to about 10microns; about 0.1 microns to about 8 microns; about 0.2 microns toabout 6 microns; about 0.5 microns to about 5 microns; about 0.5 micronsto about 4 microns; about 0.5 microns to about 3 microns; about 0.5microns to about 3 microns; about 0.1 microns to about 2 microns; about0.1 microns to about 1 micron; or about 0.1 microns to about 1 micron orless, for example about 0.8 microns. According to a preferred embodimentof the invention, the dispersed phase or the water-containing phase ofthe fuel composition comprises droplets having a mean diameter, or majordimension, of 5 microns or less. Thus emulsification is conducted underconditions sufficient to provide such a mean droplet particle size.

High-shear devices that may be used include but are not limited to theSonic Corporation Sonolator Homogenizing System, in which pressure canbe varied over a wide range, for example about 500 to about 5,000 psi;IKA Work Dispax, and shear mixers including multistage, for example,three stage rotor/stator combinations. The tip speed of the rotor/statorgenerators may be varied by a variable frequency drive that controls themotor. Silverson mixer two-stage mixer, which also incorporates arotor/stator design and the mixer employs high-volume pumpingcharacteristics similar to a centrifugal pump. Inline shear mixersemploying a rotor-stator emulsification approach (SilversonCorporation); Jet Mixers, venturi-style/cavitation shear mixers;Microfluidizer shear mixers, high-pressure homogenization shear mixers(Microfluidics Inc.); and any other available high-shear generatingmixer capable of producing the desired microemulsion, including highshear mixers selected from the group consisting of Aquashear mixers(Flow Process Technologies Inc.), pipeline static mixers, hydraulicshear devices, rotational shear mixers, ultrasonic mixing, andcombinations thereof.

Mixing of the components is preferably conducted at ambient, orsubstantially ambient, temperature conditions. It has been observed thatin some instances mixing to obtain the emulsified fuel composition isaccompanied by a slight exothermic response. Mixing can besatisfactorily conducted at temperatures in the range of about 5° C. toabout 75° C.; for example about 10° C. to about 65° C.; or about 15° C.to about 55° C.; or about 20° C. to about 45° C.; such as 22° C. toabout 35° C.

The water used in the compositions of the present invention can be fromany source. The water employed in preparing the fuel compositions of thepresent invention can be deionized, purified for example using reverseosmosis or distillation, and/or demineralized and have a low content ofdissolved minerals, for example, salts of calcium, sodium and magnesium,and will similarly include little, if any, chlorine and/or fluorine aswell as being substantially free of undissolved particulate matter.Preferably the water has been substantially demineralized by methodswell known to those skilled in the art of water treatment in order toremove dissolved mineral salts and has also been treated to remove otheradditives or chemicals, including chlorine and fluorine. The substantialabsence of such materials is expected to lead to improvements in thecondition of metal surfaces in engines and burners, particularly theinner surfaces of cylinders and nozzles. The water may be present in thewater-vegetable oil fuel emulsions at a concentration of about 1% toabout 50% by weight; alternatively about 2% to about 50% by weight;about 3% to about 40% by weight; about 4% to about 35% by weight; andabout 5% to about 30% water.

The fuels useful in the present invention are based on animal derivedoils and fats as well as on vegetable oils and fats, including mixturesthereof. Vegetable oils and fats are substances that are present, invariable percentages, in the seeds or in the fruits of various plants.In addition to those that are typically available in nature, the presentinvention can also utilize vegetable oils and fats that are obtainedfrom genetically engineered plants, including algae, and including thosethat may be developed to yield particularly high levels of oils and fatsso that they are particularly preferred sources of such materials foruse as fuels. Since the fats and oils are to be used in the compositionsof the present invention and burned as fuel, it is not necessary thatsuch fats and oils be edible. At the present time, the most common,commercially available vegetable oils, such oils being particularlyuseful herein, are obtained from the seeds of peanuts, sunflowers, soy,sesame, colza (similar in its properties to rapeseed oil, but obtainedfrom the seeds of Brassica campestris, var. oleifera), rape or canola,corn and cotton and from the fruits of palm, olive, and coconut. Thefatty substance can be obtained from treatment of the entire fruit (forexample, olive oil), the pulp (palm oil), or just the kernel (palm seedoil). All of these vegetable based or derived oils are examples of oilssuitable for use in the present invention. Other vegetable oils that maybe useful in the present invention include crambe oil, jatropha oil,linseed oil, tung oil, as well as other so-called minor oil crops asdescribed in “Minor Oil Crops,” FAO Agricultural Services Bulletin No.94, Food and Agricultural Organization of the United Nations, Rome,1992, incorporated herein by reference, such oils generally including:among the minor edible oil crops, argan; avocado; babassu palm;balanites; borneo tallow nut; brazil nut; caryocar spp; cashew nut;chinese vegetable tallow; cohune palm; the cucurbitaceae familyincluding gourd, buffalo gourd, fluted pumpkin, and marrow; smoothloofah; grapeseed; illipe; kusum; macadamia nuts; mango seed; noogabyssinia; nutmeg; perilla; pili nut; rice bran; sacha inche; seje; sheanut; and teased. Among the minor non-edible oil crops are: allanblackia;almond; chaulmoogra; cuphea spp.; jatropa curgas; karanja seed; neem;papaya; tonka bean; tung; and ucuuba. Vegetable oils are obtained fromtheir vegetable plants, seeds, etc. by methods well known in the art,including mechanical extraction or pressing as well as chemical orsolvent extraction, and are typically filtered to remove extraneousmatter in order to deliver a substantially clean product. However, it iswithin the scope of the present invention that used vegetable oil or fatfrom commercial sources can also be used, including, for example, foodfrying operations.

Furthermore, oils and fats useful in the present invention can beobtained from animal derived sources. Such animal derived or extractedoils include animal tissue extract, piscine oil, cod-liver andshark-liver oil, fish oil in general, including oil from a wide varietyof oil bearing fish some of which may be farmed for that purposeincluding fish oil currently being promoted by the Alaskan fishindustry, tallow and mixtures thereof. For purposes herein, tallowrefers to fat obtained from parts of the bodies of cattle, sheep, oxen,horses, chickens and other birds raised for food purposes, and the likeas well as similar fats, such as those obtained from plants and alsoreferred to as tallow. Large quantities of animal derived fats and oilscan be obtained as byproducts from meat rendering facilities. Mixturesof oils and fats obtained from vegetable and animal sources are alsouseful in the present invention.

In addition to or as part of the categories of vegetable and animalderived oils and fats are those oils and fats obtained from recycled oiland grease usually from restaurants and food processing plants. Suchfats and oils may originally be from vegetable or animal sources. It isto be understood that oils and fats from these sources can still beuseful even though they may require some pretreatment in order to removefood and other particulate matter as well as to reduce acidity from freefatty acids or sulfur-containing compounds that may be present, usingmethods well known to those skilled in the art.

Surfactants are known to enhance the stability of an emulsion. Asurfactant may be employed in accordance with the present invention toenhance the stability of fuel-water emulsion, particularly over time.The following tabulation provides examples of surfactants contemplatedby the invention, although useful surfactants are not limited to thosein the table. For example, also useful are surfactants disclosed in acomprehensive listing of surfactants that can be found in the spectraldatabase of Bio-Rad Laboratories (www.informatics.bio-rad.com),including infrared spectra and, in a number of cases, chemicalcomposition and chemical and physical properties and sources,incorporated herein by reference. The compounds are generallycharacterized as alcohols, nitrogen-containing compounds, esters of longchain carboxylic acids, hydrocarbons, various esters and salts of longchain carboxylic acids, sulfated and sulfonated compounds includingalkylaryl sulfonates isothionates, lignosulfonates, sulfated andsulfonated alcohols, amines, amides, carboxylic acids, carboxylic acidesters, sulfated and sulfonated polyalkoxylated materials such asesters, ethers, nitrogen compounds, aminopolycarboxylic acids such asethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaaceticacid (DTPA), and nitrilotriacetic acid (NTA), in other words EDTA, DTPA,NTA acids and salts, phosphates, silicates and silicones. To the extentthat a particular surfactant includes atoms, groups or compounds thatmay unnecessarily contribute to pollution, e.g., sulfur, its use can belimited to the amount necessary for producing and/or maintaining astable emulsion or fuel composition. Particularly preferred surfactantsinclude cetyl alcohol, hydrogenated castor oil and mixtures of cetylalcohol and hydrogenated castor oil. The following materials, referredto as surfactants herein, can be employed in accordance with thewater-fuel composition of the present invention.

Tabulation of Useful Surfactants

(A) Nonionic Surfactants:

Esters of polyhydric alcohols; alkoxylated amides; esters ofpolyoxyalkylene, polyoxypropylene and ofpolyoxyethylene-polyoxypropylene glycols; ethers of polyoxyalkyleneglycols; tertiary acetylenic glycols; and polyoxyethylated alkylphosphates.

(B) Anionic Surfactants:

Carboxylic acids and soaps; sulfated esters, amides, alcohols, ethersand carboxylic acids (all salts); sulfonated petroleum, aromatichydrocarbons, aliphatic hydrocarbons, esters, amides, amines, ethers,carboxylic acids, phenols and lignins (all salts); acylated polypeptides(salts); and phosphates.

The following specific compounds are also included. In the list thatfollows, the abbreviation “P.O.E.” refers to polyoxyethylene(polyethylene glycol) and the abbreviation “P.O.P.” refers topolyoxypropylene.

(C) Fatty Acids:

Caprylic acid, abietic acid, pelargonic acid, coconut oil fatty acids,capric acid, corn oil fatty acids, lauric acid, cottonseed oil fattyacids, myristic acid, soya oil fatty acids, palmitic acid, tallow fattyacids, stearic acid, hydrogenated fish oil fatty acids, behenic acid,tall oil fatty acids, undecylenic acid, dimer acids, oleic acid, trimeracids, erucic acid, castor oil, linoleic acid, hydrogenated castor oil,ricinoleic acid, lanolin, naphthenic acid, and lanolin fatty acids.

(D) Fatty Acid Salts:

Lithium stearate, ammonium oleate, cadmium stearate, sodium caprate,ammonium linoleate, calcium stearate, sodium laurate, ammoniumricinoleate calcium oleate, sodium myristate, ammonium naphthenates,calcium linoleate, sodium palpitate, ammonium abietate, calciumricinoleate, sodium stearate, morpholine laurate, calcium naphthenates,sodium undecylenate, morpholine myristate, cobalt stearate, sodiumoleate, morpholine palmitate, cobalt naphthenates, sodium linoleate,morpholine stearate, copper stearate, sodium ricinoleate, morpholineundecylenate, copper oleate, sodium naphthenates, morpholine oleate,copper naphthenates, sodium abietate, morpholine linoleate, ironstearate, sodium polymerized carboxylates, morpholine ricinoleate, ironnaphthenate, morpholine napthenate, lead stearate, sodium salt of talloil, morpholine abietate, lead oleate, potassium caprate,triethanolamine caprate, lead naphthenate, potassium laurate,triethanolamine laurate, magnesium stearate, potassium myristate,triethanolamine myristate, magnesium oleate, potassium palmitate,manganese stearate, potassium stearate, triethanolamine palmitate,manganese naphthenate, potassium undecylenate, triethanolamine stearate,nickel oleate, potassium oleate, strontium stearate, potassiumlinoleate, triethanolamine undecylenate, tin oleate, potassiumricinoleate, zinc laurate, potassium naphthenate, triethanolamineoleate, zinc palmitate, potassium abietate, triethanolamine linoleate,zinc stearate, ammonium caprate, triethanolamine ricinoleate, zincoleate, ammonium laurate, zinc linoleate, ammonium myristate,triethanolamine naphthenates, zinc naphthenate, ammonium palmitate, zincresinate, ammonium stearate, triethanolamine abietate, ammoniumundecylenate, aluminum palmitate, aluminum stearate, aluminum oleate,barium stearate, and barium naphthenate.

(E) Olefins:

Linear C₁₄ alpha-olefin, and linear C₁₆ alpha-olefin.

(F) Phosphorous Compounds and Mercaptans:

POE octyl phosphate, sodium phosphated castor oil, ammonium phosphatedcastor oil, 2-ethylhexyl polyphosphate sodium salt, capryl polyphosphatesodium salt, sodium di(2-ethylhexyl)phosphate, lecithin (soyphosphatides), and POE tert-dodecylmercaptoethanol.

(G) Polyethylene and Propylene Glycol Esters:

Hydroxyethyl laurate, PEG monooleate, propylene glycol monolaurate,hydroxyethoxyethyl laurate, PEG dioleate, ethylene glycolmonoricinoleate, propylene glycol monostearate, hydroxy ethoxyethoxyethyl laurate, diethylene glycol monoricinoleate, propylene glycoldilaurate, PEG monolaurate, PEG monoricinoleate, propylene glycoldistearate, PEG dilaurate, diethylene glycol coconate, ethylene glycolmonostearate, dipropylene glycol monostearate, POE coco fatty acidsester, diethylene glycol monostearate, propylene glycol monooleate, POEcastor oil, triethylene glycol monostearate, ethylene glycolhydroxystearate, propylene glycol monoricinoleate, PEG monostearate, PEGtrihydroxy stearate, propylene glycol monoisostearate, ethylene glycoldistearate, POE hydrogenated castor oil, propylene glycolmonohydroxystearate, PEG distearate, POE tall oil, PEG monoisostearate,POE abietic acid, propylene glycol dipelargonate, PEG diisostearate, POElanolin, hydroxyethyl oleate, acetylated lanolin, isopropylester oflanolin fatty acids, hydroxyethoxyethyl oleate, POE lanolin acetylated,methoxy PEG monooleate, POE propylene glycol monostearate, and hydroxyethoxyethoxy ethyl oleate.

(H) Alcohols, Phenols and Polyoxyethylene Derivates:

Stearyl alcohol, oleyl alcohol, octyl phenol, nonyl phenol,tert-octylphenoxy ethanol, p-dodecyl phenol, dinonyl phenol, tridecylalcohol, tetradecyl alcohol, lanolin alcohols, cholesterol, dimethylhexynol, dimethyl octynediol, tetramethyl decynediol, POE tridecylphenyl ether, POE lanolin alcohol ether, POE cholesterol, POEn-octylphenol, POE tert-octylphenol, POE nonylphenol, POE dinonylphenol, POE dodecyl phenol, POE lauryl alcohol ether, POE cetyl alcoholether, POE stearyl alcohol ether, POE tetramethyldecynediol, POE oleylalcohol ether, POP EtO, POE isohexadecyl alcohol ether2,6,8-trimethyl-4-nonyloxypolyethyleneoxyethanol,polyoxypropylene-polyoxyethylene block copolymer, alkyl ether ofPOE/POP, and POE tridecyl alcohol ether.

(J) Glycerol Esters:

Glycerol monocaprylate, glycerol monolaurate, glycerol mono/dicocoate,glycerol dilaurate, glycerol monostearate, glycerol monostearatedistilled, glycerol distearate, glycerol monooleate, glycerol dioleate,glycerol trioleate, glycerol monoisostearate, glycerol monoricinoleate,glycerol monohydroxystearate, POE glycerol monostearate, acetylatedglycerol monostearate, succinylated glycerol monostearate, diacetylatedglycerol monostearate tartrate, modified glycerol phthalate resin,triglycerol monostearate, triglycerol monooleate, triglycerolmonoisostearate, decaglycerol tetraoleate, decaglycerol decastearate,pentaerythritol monolaurate, pentaerythritol monostearate,pentaerythritol distearate, pentaerythritol tetrastearate,pentaerythritol monooleate, pentaerythritol dioleate, pentaerythritoltrioleate, pentaerythritol tetraricinoleate, sorbitan monolaurate, POEsorbitan monolaurate, sorbitan monopalmitate, POE sorbitanmonopalmitate, sorbitan monostearate, POE sorbitan monostearate,sorbitan tristearate, POE sorbitan tristearate, sorbitan monooleate, POEsorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, POEsorbitan trioleate, POE sorbitol hexaoleate, POE sorbitol oleatelaurate, POE sorbitol polyoleate, POE sorbitol, beeswax-ester, sucrosemonolaurate, sucrose cocoate, sucrose monomyristate, sucrosemonopalmitate, sucrose dipalmitate, sucrose monostearate, sucrosedistearate, sucrose monooleate, sucrose dioleate, lauryl lactate, cetyllactate, sodium lauryl lactate, sodium stearoyl lactate, sodiumisostearoyl-2-lactylate, sodium stearoyl-2-lactylate, calciumstearoyl-2-lactylate, sodium capryl lactate, lauryl alcohol, and cetylalcohol.

(K) Amides and Amide Derivatives:

Stearamide, oleamide, erucamide, behenamide, lauric acidmonoethanolamide, tallow monoethanolamide, POE lauric amide, myristicacid diethanolamide, stearic acid diethanolamide, oleic aciddiethanolamide, POE oleic amide, coco acid diethanolamide, POE cocoamide, POE hydrogenated tallow amide, lauric acid monoisopropanolamide,and oleic acid monoisopropanolamide.

(L) Sulfates:

Sodium n-octyl sulfate, sodium 2-ethylhexyl sulfate, sodium decylsulfate, sodium lauryl sulfate, sodium tridecyl sulfate, sodiumsec-tetradecyl sulfate, sodium cetyl sulfate, sodium sec-heptadecylsulfate, sodium oleyl sulfate, sodium oleyl stearate sulfate, sodiumtridecyl ether sulfate, potassium lauryl sulfate, magnesium laurylsulfate, triethanolamine lauryl sulfate, ammonium lauryl sulfate,diethanolamine lauryl sulfate, triethanolammonium lauryl sulfate, POEoctylphenol sodium salt, alkylaryl polyether sulfate sodium salt,sulfated POE nonylphenol sodium salt, sulfated nonylphenyl ether oftetraethyleneglycol ammonium salt, sulfated lauryl ether oftetraethyleneglycol sodium salt, POE sodium lauryl monoether sulfate,POE sodium lauryl ether sulfate, POE ammonium lauryl sulfate, sulfatedoleic acid sodium salt, sulfated castor oil-fatty acids sodium salt,sulfated propyloleate sodium salt, sulfated isopropyloleate sodium salt,sulfated butyloleate sodium salt, sulfated glycerol monolaurate sodiumsalt, sulfated glycerol trioleate sodium salt, sulfated castor oilsodium salt, sulfonated marine oil, sulfated neatsfoot oil sodium salt,sulfated rice bean oil sodium salt, sulfated soya bean oil sodium salt,sulfated synthetic sperm oil, and sulfated tallow sodium salt.

(M) Miscellaneous Surfactant Compounds:

Perfluoro surfactant-anionic, perfluoro surfactant-cationic,ethylenediamine tetraacetic acid disodium salt,ethylenediaminetetraacetic acid tetrasodium salt, sodium dihydroxyethylglycinate, trisodium nitrilotriacetate, sodium citrate, siliconedefoamer-oil, silicone defoamer-water dispersible, sodium tetraborate,sodium carbonate, sodium phosphate-tribasic, sodium silicate, and alkylbenzene sulfonic acid-propylene tetramer.

(N) Sulfonates:

Sodium toluene sulfonate, sodium xylene sulfonate, sodium cumenesulfonate, sodium dodecylbenzene sulfonate, sodium tridecylbenzenesulfonate, sodium kerylbenzene sulfonate, calcium dodecylbenzenesulfonate, ammonium xylene sulfonate, triethanolammonium dodecylbenzenesulfonate, alkylammonium dodecyl-benzene sulfonate, aliphatichydrocarbons-sulfonic acid, sodium petroleum sulfonate, calciumpetroleum sulfonate, Bryton barium sulfonate, magnesium petroleumsulfonate, ammonium petroleum sulfonate, isopropylamine petroleumsulfonate, ethylenediamine petroleum sulfonate, triethanolaminepetroleum sulfonate, sulfonated napthalene sodium diisopropylnaphthalene sulfonate, sodium dibutyl naphthalene sulfonate, sodiumbenzyl naphthalene sulfonate, sodium naphthalene formaldehyde-condensatesulfonate, sodium polymerized alkylnaphthalene sulfonate, potassiumpolymerized alkylnaphthalene sulfonate, ammonium dibutylnaphthalenesulfonate, ethanolamine dibutylnaphthalene sulfonate, sodiumsulfooleate, sodium monobutylphenylphenol monosulfonate, disodiumdibutylphenylphenol disulfonate, potassium monoethylphenylphenolmonosulfonate, ammonium monoethylphenylphenol monosulfonate, guanidiniummonoethylphenylphenol monosulfonate, sodium decyldiphenyletherdisulfonate, sodium dodecyldiphenylether disulfonate, calciumpolymerized alkyl-benzene sulfonate, sulfonated polystyrene, sulfonatedaliphatic polyester, sodium-2-sulfoethyl oleate, sodium amylsulfooleate, sodium lauryl sulfoacetate, sodium diisobutylsulfosuccinate, sodium diamyl sulfosuccinate, sodium dihexylsulfosuccinate, sodium dioctyl sulfosuccinate, sodium ditridecylsulfosuccinate, sodium alkylarylpolyether sulfonate, and sodiumlignosulfonate.

(O) Amines and Amine Derivatives:

tert-C₁₁-C₁₄ amine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine,n-octadecylamine, C₁₈-C₂₄ amine, oleylamine, cocoamine, hydrogenatedtallow amine, tallow amine, POE tert-amine, POE stearyl amine, POE oleylamine, C₁₂-C₁₄ tert-alkylamines, ethoxylated POE cocoamine, POE tallowamine, POE soya amine, POE octadecylamine, N-b-hydroxyethyl stearylimidazoline, POE (3) N-tallow trimethylene diamine, N-b-hydroxyethylcocoimidazoline, N-b-hydroxyethyl oleyl imidazoline, n-dodecylamineacetate, hexadecylamine acetate, octadecylamine acetate oleylamineacetate, cocoamine acetate, hydrogenated tallow amine acetate, tallowamine acetate, soya amine acetate,N-stearyl-N′,N′-diethylethylene-diamine acetate, N-oleylethylenediamineformate, cocoamidopropyl dimethyl amine oxide, lauryl dimethylamineoxide, myristyl dimethylamine oxide, soya amine, diococoamine,dihydrogenated tallow amine, dimethyl hexadecylamine, dimethyloctadecylamine, dimethyl cocoamine, dimethyl soyaamine,N-coco-1,3-diaminopropane, N-soya-1,3-diaminopropane,N-tallow-1,3-diaminopropane, N-coco-b-aminobutyric acid, stearamidoethyldiethylamine, sodium-N-coco-b-amino propionate, N-tallow trimethylenediamine diacetate, disodium-N-tallow-b-imino dipropionate,disodium-N-lauryl-b-imino dipropionate, cetyl betaine, coco betaine,myristamidopropyl betaine, oleyl betaine, coconut amido betaine, oleylamido betaine, coconut oil acid ester of sodium isethionate, cocoamidoalkyldimethylamine, behenic amido alkyl dimethylamine, isostearic amidoalkyl dimethylamine, oleic amido alkyl dimethylamine,sodium-N-methyl-N-palmitoyl taurate, sodium-N-methyl-N-oleyl taurate,sodium-N-coconut acid N-methyl taurate, sodium-N-methyl-N-tall oiltaurate, N-lauryl sarcosine, cocoyl sarcosine, N-oleyl sarcosine,sodium-N-lauryl sarcosinate, sodium carboxymethylnonylhydroxy-ethyimidazolinium hydroxide, sodium carboxymethylundecylhydroxy-ethylimidazolinium hydroxide, sodium carboxymethylcocohydroxy-ethylimidazolinium hydroxide, sodium carboxyethyloleylhydroxy-ethylimidazolinium hydroxide, sodium carboxymethylstearylhydroxy-ethylimidazolinium hydroxide, and sodium carboxymethylsodiumcarboxy-ethylcocoether imidazolinium.

(P) Quaternary Amine Salts:

Dodecyltrimethyl ammonium chloride, hexadecyltrimethyl ammoniumchloride, octadecyltrimethyl ammonium chloride, cetyltrimethyl ammoniumbromide, cetyldimethylethyl ammonium bromide, coco trimethyl ammoniumchloride, tallow trimethyl ammonium chloride, soya trimethyl ammoniumchloride, dicoco dimethyl ammonium chloride, dimethyl 80% behenyl benzylammonium chloride, methyl bis(2-hydroxyethyl)coco ammonium chloride,dihydrogenated tallow dimethyl ammonium chloride, methyldodecylbenzyltrimethyl ammonium chloride, n-alkyl dimethyl benzyl ammonium chloride,alkyldimethyl-3,4-dicholor-benzyl ammoniumchloride,octylphenoxyethoxyethyl dimethyl-benzyl ammonium chloride,octylcresoxyethoxyethyl dimethyl-benzyl ammonium chloride,cocoamidopropyl PG-dimonium chloridephosphate, 2-hydroxyethylbenzylstearyl imidazolinium chloride, 2-hydroxyethylbenzyl coco imidazoliniumchloride, ethyl bis(polethoxyethanol)alkyl ammonium chloride, diethylheptadecyl imidazolinium ethylsulfate, lauryldimethylbenzyl ammoniumchloride, stearyldimethylbenzyl ammonium chloride, laurylpyridiniumchloride, 1-hexadecylpyridinium chloride, cetylpyridinium bromide,lauryl isoquinolinium bromide, and substituted oxazoline.

In one embodiment the emulsifier or surfactant comprises at least onesorbitan ester. The sorbitan esters include sorbitan fatty acid esterswherein the fatty acid component of the ester comprises a carboxylicacid of about 10 to about 100 carbon atoms, and in one embodiment about12 to about 24 carbon atoms. Sorbitan is a mixture of anhydrosorbitols,principally 1,4-sorbitan and isosorbide (Formulas I and II):

Sorbitan, (also known as monoanhydrosorbitol, or sorbitol anhydride) isa generic name for anhydrides derivable from sorbitol by removal of onemolecule of water. The sorbitan fatty acid esters of this invention area mixture of partial esters of sorbitol and its anhydrides with fattyacids. These sorbitan esters can be represented by the structure belowwhich may be any one of a monoester, diester, triester, tetraester, ormixtures thereof (Formula III):

In formula (III), each Z independently denotes a hydrogen atom orC(O)R—, and each R mutually independently denotes a hydrocarbyl group ofabout 9 to about 99 carbon atoms, more preferably about 11 to about 23carbon atoms. Examples of sorbitan esters include sorbitan stearates andsorbitan oleates, such as sorbitan stearate (i.e., monostearate),sorbitan distearate, sorbitan tristearate, sorbitan monooleate andsorbitan sesquioleate. Sorbitan esters are available commercially underthe trademarks “Span” and “Arlacel” from ICI. The sorbitan esters alsoinclude polyoxyalkylene sorbitan esters wherein the alkylene group hasabout 2 to about 30 carbon atoms. These polyoxyalkylene sorbitan esterscan be represented by Formula IV:

wherein in Formula IV, each R independently is an alkylene group ofabout 2 to about 30 carbon atoms; R′ is a hydrocarbyl group of about 9to about 99 carbon atoms, more preferably about 11 to about 23 carbonatoms; and w, x, y and z represent the number of repeat oxyalkyleneunits. For example ethoxylation of sorbitan fatty acid esters leads to aseries of more hydrophilic: surfactants, which is the result of hydroxygroups of sorbitan reacting with ethylene oxide. One principalcommercial class of these ethoxylated sorbitan esters are thosecontaining about 2 to about 80 ethylene oxide units, and in oneembodiment from about 2 to about 30 ethylene oxide units, and in oneembodiment about 4, in one embodiment about 5, and in one embodimentabout 20 ethylene oxide units. They are available from Calgene Chemicalunder the trademark “POLYSORBATE” and from ICI under the trademark“TWEEN”. Typical examples are polyoxyethylene (hereinafter “POE”) (20)sorbitan tristearate (Polysorbate 65; Tween 65), POE (4) sorbitanmonostearate (Polysorbate 61; Tween 61), POE (20) sorbitan trioleate(Polysorbate 85; Tween 85), POE (5) sorbitan monooleate (Polysorbate 81;Tween 81), and POE (80) sorbitan monooleate (Polysorbate 80; Tween 80).As used herein the number within the parentheses refers to the number ofethylene oxide units present in the composition.

The following is a list of emulsifiers that may be particularly useful:

Product Name* Synonym HLB 2,4,7,9-Tetramethyl-5-decyne- 4.0 4,7-diolPEG-block-PPG-block-PEG, Mn = 1100 4.0 PEG-block-PPG-block-PEG, Mn =2000 4.0 PEG-block-PPG-block-PEG, Mn = 2800 4.0 PEG-block-PPG-block-PEG,Mn = 4400 4.0 Ethylenediamine tetrakis(PO-b- 4.0 EO) tetrol, Mn = 3600Ethylenediamine tetrakis(EO-b- 4.0 PO) tetrol, Mn = 7200 Ethylenediaminetetrakis(EO-b- 4.0 PO) tetrol, Mn = 8000 Igepal CA-210Polyoxyethylene(2) 4.3 isooctylphenyl ether Span 80 Sorbitan monooleate4.3 PPG-block-PEG-block-PPG, Mn = 3300 4.5 Igepal CO-210Polyoxyethylene(2) nonylphenyl 4.6 ether Span 60 Sorbitan monostearate4.7 Brij 92 Polyoxyethylene(2) oleyl ether 4.9 Brij 72Polyoxyethylene(2) stearyl ether 4.9 Brij 52 Polyoxyethylene(2) cetylether 5.3 Span 40 Sorbitan monopalmitate 6.7 Merpol A surfactantNonionic, ethylene oxide 6.7 condensate 2,4,7,9-Tetramethyl-5-decyne-8.0 4,7-diol ethoxylate Triton SP-135 8.0 Span 20 Sorbitan monolaurate8.6 PEG-block-PPG-block-PEG, Mn = 5800 9.5 PPG-block-PEG-block-PPG, Mn =2700 9.5 Brij 30 Polyoxyethylene(4) lauryl ether 9.7 Igepal CA-520Polyoxyethylene(5) 10.0 isooctylphenyl ether Igepal CO-520Polyoxyethylene(5) nonylphenyl 10.0 ether Polyoxyethylene sorbitol 10.2hexaoleate Merpol SE surfactant 10.5 Tween 85 Polyoxyethylene(20)sorbitan 11.0 trioleate 8-Methyl-1-nonanol propoxylate- 11.0block-ethoxylate Polyoxyethylene sorbitan 11.4 tetraoleate Triton X-114Polyoxyethylene(8) 12.4 isooctylphenyl ether Brij 76 Polyoxyethylene(10)stearyl 12.4 ether Brij 97 Polyoxyethylene(10) oleyl ether 12.4 MerpolOJ surfactant 12.5 Brij 56 Polyoxyethylene(10) cetyl ether 12.9 MerpolSH surfactant 12.9 2,4,7,9-Tetramethyl-5-decyne- 13.0 4,7-diolethoxylate (5 EO/OH) Triton SP-190 13.0 Igepal CO-630 Polyoxyethylene(9)nonylphenyl 13.0 ether Triton N-101 Polyoxyethylene branched 13.4nonylphenyl ether Triton X-100 Polyoxyethylene(10) 13.5 isooctylphenylether Igepal CO-720 Polyoxyethylene(12) nonylphenyl 14.2 etherPolyoxyethylene(12) tridecyl 14.5 ether Polyoxyethylene(18) tridecyl14.5 ether Igepal CA-720 Polyoxyethylene(12) 14.6 isooctylphenyl etherTween 80 Polyoxyethylene(20) sorbitan 14.9 monooleate Tween 60Polyoxyethylene(20) sorbitan 15.0 monostearate PEG-block-PPG-block-PEG,Mn = 2900 15.0 PPG-block-PEG-block-PPG, Mn = 2000 15.0 Brij 78Polyoxyethylene(20) stearyl 15.3 ether Brij 98 Polyoxyethylene(20) oleylether 15.3 Merpol HCS 15.5 surfactant Tween 40 Polyoxyethylene(20)sorbitan 15.6 monopalmitate Brij 58 Polyoxyethylene(20) cetyl ether 15.7Polyoxyethylene(20) hexadecyl 15.7 etherPolyethylene-block-poly(ethylene 16.0 glycol), Mn = 2250 Tween 20Polyoxyethylene(20) sorbitan 16.7 monolaurate Brij 35Polyoxyethylene(23) lauryl ether 16.9 2,4,7,9-Tetramethyl-5-decyne- 17.04,7-diol ethoxylate (15 EO/OH) Igepal CO-890 Polyoxyethylene(40)nonylphenyl 17.8 ether Triton X-405 Polyoxyethylene(40) 17.9isooctylphenyl ether Brij 700 Polyoxyethylene(100) stearyl 18.8 etherIgepal CO-990 Polyoxyethylene(100) nonylphenyl 19.0 ether Igepal DM-970Polyoxyethylene(150) 19.0 dinonylphenyl ether PEG-block-PPG-block-PEG,Mn = 1900 20.5 PEG-block-PPG-block-PEG, Mn = 8400 24.0 Ethylenediaminetetrakis(PO-b- 24.0 EO) tetrol, Mn = 15000 PEG-block-PPG-block-PEG,average 27.0 Mn = ca. 14,600 *Abbreviations: Mn = number averagemolecular weight; PEG = polyethylene glycol; PPG = polypropylene glycol;EO = ethylene oxide; PO = propylene oxide; HLB = hydrophilic-lipophilicbalance.

Useful emulsifiers of the types listed in the above table can begenerically represented by the following classes of chemical compounds,members of which are commercially available and are suitable providedthat they are used in accordance with the teachings herein such thatstable emulsified compositions are produced:

(a) sorbitol esters of the general formula

in which: the radicals X are identical to or different from one anotherand are each OH or R¹COO⁻, where R¹ is a linear or branched, saturatedor unsaturated, aliphatic hydrocarbon radical optionally substituted byhydroxyls and having from 7 to 22 carbon atoms, provided that at leastone of said radicals X is R¹COO⁻,

(b) fatty acid esters of the general formula

in which: R² is a linear or branched, saturated or unsaturated,aliphatic hydrocarbon radical optionally substituted by hydroxyl groupsand having from 7 to 22 carbon atoms,

-   R³ is a linear or branched C₁-C₂₀ alkylene,-   n is an integer greater than or equal to 6, and-   R⁴ is H, linear or branched C₁-C₁₀ alkyl or

where R⁵ is as defined above for R²; and

(c) polyalkoxylated alkylphenol of the general formula

in which: R⁶ is a linear or branched C₁-C₂₀ alkyl,

-   m is an integer greater than or equal to 8, and-   R⁷ and R⁸ are respectively as defined above for R³ and R⁴ of formula    (II).

Particularly useful emulsifiers include compounds exhibiting ahydrophilic-lipophilic balance (HLB, which refers to the size andstrength of the polar (hydrophilic) and non-polar (lipophilic) groupsthat comprise the emulsifier or surfactant molecule) typically in therange of about 1 to about 40; in another embodiment about 5 to about 20.HLB is a well-known parameter utilized by those skilled in the art forcharacterizing emulsifiers. It is defined in detail, for example, in thereferences “Emulsions: Theory and Practice, P. Becher, ReinholdPublishing Corp., ACS Monograph, ed. 1965”, in the chapter “Thechemistry of emulsifying agents” (pg. 232 et seq.); and also in Handbookof Applied Surface and Colloid Chemistry, K. Holmberg (Ed.), “Chapter11, Surface Chemistry in the Petroleum Industry,” J. R. Kanicky et al.,251-267, which also describes a method for calculating HLB values basedon chemical structure; these references incorporated herein by referenceto the extent permitted. A well established empirical procedure fordetermining HLB values for a given emulsifier may be determinedexperimentally by the method of W. C. Griffin, J. Soc. Cosmetic Chem.,1, 311 (1949), incorporated herein by reference to the extent permitted.Examples of suitable compounds are included in the above table and arealso disclosed in McCutcheon's Emulsifiers and Detergents, 1998, NorthAmerican Edition (pages 1-235) & International Edition (pages 1-199),incorporated herein by reference for their disclosure of compoundshaving an HLB in the range of about 1 to about 40; in one embodimentabout 1 to about 30; in one embodiment about 1 to 20; and in anotherembodiment about 4 to about 18; alternatively, greater than about 8, forexample about 8.5 or about 9 to about 18. Various useful compoundsinclude those identified in the above table, including for example,sorbitan monolaurate, polyoxyethylene(20) sorbitan monooleate, andpolyoxyethylene(20) sorbitan monolaurate.

It is also possible to obtain stable emulsified fuel compositions usinga combination of emulsifiers. For purposes of explanation and notlimitation, for example instead of a single emulsifier having an HLBvalue of about 12 an emulsified fuel composition can be prepared using amixture of emulsifiers, such as a 50/50 mixture two emulsifiers, onehaving an HLB value of about 16 and the other an HLB value of about 8.Similarly combinations of three or more emulsifiers can also be used,provided that the HLB value of the mixture exhibits the desired overallvalue and the effect of the mixture is to provide a stable emulsion. Forpurposes of a mixed emulsifier composition, the HLB value of theemulsifier mixture is calculated as a linear sum weighted average basedon the weight fraction that each of the emulsifiers represents comparedto the total amount of emulsifier present:

HLB_(m)=Σ[(HLB_(n))(wt_(n)/wt_(tot))]

where:

Σ=Sum of the values shown in brackets

HLB_(m)=the HLB value of one or a mixture of emulsifiers;

n=number of emulsifiers present in the mixture, wherein any number ofemulsifiers can be used; typically n=1 to about 5; more typically 1 toabout 4; or 1 to about 3; or 1 to about 2. For example, it is suitableto use mixtures of 2, 3 or 4 emulsifiers to obtain a stable emulsion;

HLB_(n)=the HLB value of a single emulsifier if n=1 or the HLB value ofeach emulsifier in a mixture of emulsifiers;

wt_(n)=the weight, for example in grams, of each emulsifier in a mixtureof emulsifiers; and

wt_(tot)=the total weight of all emulsifiers present in a mixture ofemulsifiers.

In a preferred embodiment a mixture of two emulsifiers is used whereinone emulsifier has an HLB value of equal to or less than about 6, forexample about 1 to about 6.0, or about 2 to about 5.9, or about 3 toabout 5.5, or about 4 to about 5.9, and the like; and the secondemulsifier has an HLB value of greater than about 6, for example about 6to about 20; or about 6.1 to about 18, or about 6.5 to about 16, orabout 7 to about 15, and the like; provided that both emulsifiers do nothave an HLB value of 6. Alternatively, one emulsifier comprising abimodal distribution of chemical species exhibiting each of the HLBproperties can be used.

The use of multiple emulsifiers in the same emulsified fuel compositioncan be advantageous in compositions in which the total concentration ofhydrophilic components is low. For example, compositions in which thewater concentration is less than about 5 wt %, such as about 1 wt % toabout 5 wt %, or about 1 wt % to about 4 wt %, or 1 wt % to about 3 wt%, or 1 wt % to about 2 wt %. Alternatively, the concentrations ofvarious hydrophilic or substantially hydrophilic components can be addedtogether for consideration of the above recited concentrations,including water, hydroxyl-containing component(s) such as one or morealcohols or glycols and the like. In particular, if the ratio of thetotal amount of such hydrophilic components to the total amount oflipophilic components, the latter including but not limited to theanimal and vegetable fats and oils, is equal to or less than about 0.25,for example, about 0.05 to about 0.25 or any specific valuetherebetween, including, for example, about 0.06, 0.08, 0.10, 0.12,0.14, 0.16, 0.18, 0.20, 0.22 or 0.24, it is desirable to use a mixtureof emulsifiers as described above; in other words, emulsifier mixtureswherein at least one emulsifier has an HLB value of equal to or lessthan about 6 and at least one emulsifier has an HLB value of greaterthan about 6 (subject to the provisos expressed above). For example, acomposition comprising, in wt %, 80 of vegetable oil, 4 of water and 14of ethanol (e.g., 95 wt % ethanol containing 5 wt % water and/ordenaturants) results in a calculated ratio of 18/80=0.225. To prepare astable emulsion using such components it is preferable to employ amixture of emulsifiers, for example, a 50/50 mixture of an emulsifierhaving an HLB value of, for example, about 4 and one having an HLB valueof about 15. In contrast, a stable emulsified composition can beprepared using a single emulsifier where the lipophilic and hydrophiliccomponents comprise 75 wt % vegetable oil, 1 wt % water, and 23 wt %alcohol. Alternatively, a mixture of emulsifiers can be used even wherethe calculated ratio is greater than 0.25, particularly if the value isonly slightly greater, for example about 5% to about 10% greater.Optionally, a mixture of emulsifiers can be used if desired;particularly if it is anticipated that the user of such a fuelcomposition may subsequently introduce an additive into the compositionthat might have the effect of changing the calculated ratio.

Alcohols useful in the present invention include hydroxyl-containingorganic compounds selected from the group consisting of (A) monohydric(one OH group) alcohols characterized as (1) aliphatic, includingstraight and branched chain, and sub-characterized within this group asparaffinic (for example, ethanol) and olefinic (for example, allylalcohol); (2) alicyclic (for example, cyclohexanol); (3) aromatic (forexample, phenol, benzyl alcohol); (4) heterocyclic (for example,furfuryl alcohol); and (5) polycyclic (for example, sterols); (B)dihydric (two OH groups), including glycols and derivatives (forexample, diols); (C) trihydric (three OH groups), including glycerol andderivatives; and (D) polyhydric (polyols), having three or four or moreOH groups). In particular, useful alcohols include alcohols selectedfrom the group consisting of C1 to C4 straight and branched chainmonoalcohols, C2 to C4 mono- and polyalkylene glycols including ethyleneglycol, diethylene glycol, triethylene glycol, propylene glycol,dipropylene glycol, tripropylene glycol, derivatives of C2 to C4 mono-and polyalkylene glycols provided that the molecular weights of suchpolyalkylene glycols are suitable for use in the fuel compositions ofthe present invention, and mixtures thereof. Fuel compositions in whicha monoalcohol is included also preferably include at least one oftert-butyl alcohol, at least one C2-C4 alkylene glycol or a mixture ofboth. Ethyl alcohol or ethanol and propylene glycol are particularlypreferred in the compositions of the present invention. Ethanol isavailable commercially in the anhydrous form (also referred to asabsolute alcohol or 100% ethanol) and as various proofs or percentagesof ethanol where the additional component in the ethanol is water, themost common being 190 proof or 95 vol %. If ethanol is used for purposesother than as a beverage, it is denatured by addition of substances,such as methanol, 2-propanol, ethyl acetate, methyl isobutyl ketone,heptane or kerosene, to make the product undesirable for humanconsumption, but allows for its use for industrial purposes, includingas a component in fuel or as a fuel. As noted, ethanol other thanabsolute ethanol is typically identified by use of the term “proof,”where the conversion between proof and the concentration of ethylalcohol is that 2 proof equals 1% by volume, typically measured at 20°C., although measurements at other temperatures are also accepted,including e.g., 15.6° C. while various denaturants are available thatcan render ethanol (with or without the presence of moisture or water)unsuitable for human consumption, certain of such denaturants may not besuitable for use in connection with fuels because of their adverseeffects on fuel stability, vehicle engines and fuel systems andemissions. A list of denaturants used in connection with ethyl alcoholfor various purposes can be found in The Merck Index, ThirteenthEdition, 2001, entry 3796, page 670, incorporated herein by reference.Physical properties of ethanol can vary depending on whether ethanol isanhydrous, mixed with water to various concentrations, and whether it isdenatured and the type of denaturant used. Denaturants that may beunsuitable for use in connection with fuels are known to those skilledin the art and are often specified by various governmental agencies. Forexample, the Indian government prohibits the use of methanol, pyrroles,turpentine, ketones and tars (high molecular weight pyrolysis productsof fossil or non-fossil vegetable matter). The standards in ASTM D4806and ASTM D5798, incorporated herein by reference, describe the amountand types of denaturants typically permitted for use in fuels and alsoidentifies others that should not be used in view of their potentiallyadverse effects, as noted above. Furthermore, ASTM D5798 also describesthe standards for fuels for use in engines that are designed to utilizeethanol as a substitute for petroleum, i.e., that include substantiallyhigh percentages of ethanol. Absolute ethyl alcohol is ordinarilyunderstood to mean ethyl alcohol containing no more than 0.5 vol. %water, although for purposes of the present invention, such a moisturelimitation has little significance. When used in the vegetable oilemulsion fuel composition of the present invention, alcohol or a mixtureof the alcohols identified herein as useful, are included at aconcentration of about 1 wt % to about 25 wt % based on the total weightof the fuel composition; or about 2 wt % to about 22 wt %; or about 3 wt% to about 20 wt %; or about 4 wt % to about 18 wt %; or about 5 wt % toabout 20 wt %; or about 1 wt % to about 15 wt %; or about 1 wt % toabout 10 wt %; or about 1 wt % to about 5 wt %; or about 2 wt % to about6 wt %; alternatively, about 3 wt % to about 8 wt %.

Alternatively, the C4 alcohol butyl alcohol is also useful in thepresent invention. Where butyl alcohol is used it is preferred to usetert-butyl alcohol because it is more readily soluble in water. However,since n-butyl alcohol and sec-butyl alcohol are not completely solublein water, their use can require a further adjustment in the type andamount of emulsifier in the fuel composition in order to obtain a stableemulsion. Tert-butyl alcohol can be used in place of or in combinationwith ethanol, for example including mixtures in which the relativeamount, by weight, of ethanol to tert-butyl alcohol is about 95/5 to5/95; including useful amounts therebetween such as about 85/15, 80/20,75/25, 70/30, 65/35, 60/40, 55/45, 50/50, 45/55, 40/60, 35/65, 30/70,25/75, 20/80, 15/85, and about 10/90.

The water-vegetable oil fuel emulsions comprise: a continuous vegetableoil fuel phase; a discontinuous water or aqueous phase being comprisedof aqueous droplets preferably having a mean diameter of about 10microns or less, for example, 5 microns; and an emulsifying amount of atleast one emulsifier. The emulsions may be prepared by various steps orsequences of addition as described herein, including for example, (1)mixing the vegetable oil, emulsifier and other desired additives usingstandard mixing techniques to form a vegetable oil-emulsifier mixture;and (2) mixing the vegetable oil-emulsifier mixture with water (andoptionally additional additives, including for example ethanol,propylene glycol, cetane improver, or mixtures thereof) underemulsifying mixing conditions to form the desired water-vegetable oilfuel emulsion.

Optionally, additives may be added to the emulsifier, the vegetable oil,the water or combinations thereof. The additives include but are notlimited to cetane improvers, organic solvents, other fuels such asdiesel fuel, glycols, surfactants or emulsifiers, other additives knownfor their use in fuel and the like. The additives are added to theemulsifier, vegetable oil or the water prior to and in the alternativeat the emulsification device(s) depending upon the solubility or otherfluid properties of the additive. The additives are generally in therange of about 1% to about 40% by weight, in another embodiment about 5%to about 30% by weight, and in another embodiment about 7% to about 25%by weight of the fuel mixture.

The vegetable oil fuel emulsifier mixtures contain about 50% to about95% by weight, in another embodiment about 55% to about 90% by weight;and in another embodiment about 60% to about 85% by weight vegetable oilfuel, and it further contains about 0.05% to about 10%, in anotherembodiment about 0.1% to about 10%, and in another embodiment about 1%to about 5% by weight of at least one emulsifier.

The water, which can optionally include but is not limited to one ormore alkylene glycol, alcohol, cetane improver or mixtures thereof. Inone embodiment the water, alcohol and/or alkylene glycol and/or thecetane improver are mixed with one another and fed continuously to thefuel additives stream. In another embodiment the water, alcohol and/oralkylene glycol and/or the cetane improver or mixtures thereof flow outof separate tanks and/or combinations thereof into or mixed prior to theemulsification device. In one embodiment the water, alcohol and/oralkylene glycol and/or the cetane improver mixture meets. the vegetableoil fuel additives mixture immediately prior to or in the emulsificationdevice.

Alternative methods are available for preparing one embodiment theemulsified fuel of the present invention. For example, vegetable oil ora vegetable oil mixture and a major proportion, or all, of the desiredamount of C1-C4 alcohol, such as ethanol, are mixed with one another toform a two phase composition with the alcohol as the upper phase. Whenthe water and remaining component(s), including emulsifier(s), are addedwith agitation, a stable, emulsified composition is produced.Alternatively, the C1-C4 alcohol, or a proportion thereof, including amajor proportion, e.g., greater than 50 wt %, can be mixed with thecomponents other than the water, to which the vegetable oil is added,which results in a two phase mixture with the oil as the upper phase. Ifa split addition of alcohol is used, any convenient fraction can be usedas a two-phase mixture results until the water is added. Addition ofwater to this mixture with agitation produces a stable, emulsifiedcomposition. If desired, either of the described two phase mixtures canbe produced and stored until such time as it is desired to add the watercomponent, with the additional component(s) if required, to form thestable, emulsified composition. Furthermore, the two-phase mixtures canbe shipped to a desired location before addition of the water in orderto reduce the burden of shipping water in the mixture.

An optional component of the fuel mixture referred to as supplementarycombustible liquid can be “paint thinner,” turpentine or mineralspirits. Materials of this type are generally described in U.S. Pat. No.5,609,678, incorporated herein by reference in its entirety.Alternatively, the use of this component in the present invention can becharacterized as a low viscosity, low density supplementary combustibleliquid additive. Such an optional component can be useful for thepurpose of modifying one or more properties of the fuel composition,including, for example, the cetane number, density and viscosity.Consequently, the amount and type of such component can be selectedbased on its combustion properties as measured by the cetane number ofthe resulting fuel composition, by the density of the resultingcomposition and by its viscosity as well as its effect on the phasedistribution of the microemulsion in view of the amount and type ofsurfactant used. In each instance the amount of the liquid added can besuitably adjusted to produce a fuel composition having the overallbalance of properties suitable for the end use of the fuel product, forexample, as a fuel for a diesel engine, a furnace, etc., or foradjusting the properties of the fuel composition for the ambienttemperature environment in which it is intended to be used, for example,as an automotive diesel fuel for winter or summer use.

Useful supplementary combustible liquid additives of the paint thinnertype include products identified as hydrotreated, light steam crackednaphtha residuum (petroleum), also referred to as naphtha, petroleum,hydrotreated heavy, and identified as CAS 64742-48-9. This product hasalso been described as a complex combination of hydrocarbons obtained bytreating a petroleum fraction with hydrogen in the presence of acatalyst. It typically comprises hydrocarbons having carbon numberspredominantly in the range of C6 through C13 and boiling in the range ofapproximately 65° C. to 230° C. (149° F. to 446° F.). Several of itscharacteristic physical properties include the following: boiling point,155-217° C.; melting point, 0° C.; density, 0.76-0.79 g/cm³; vaporpressure, 0.1-0.3 kPa @ 20° C.; flash point, 40-62° C.; auto-ignitiontemperature, 255-270° C.; explosive limits, 0.7-6.0 vol % in air. Asuitable material is available commercially from Italchimica LazioS.r.l. (Monterotondo Scalo, Italy). A particularly useful product is onethat is treated such that it is further described as “odorless,” as thatterm is understood in the art. This product has a viscosity of 1.23mm²/s (ASTM D445) and a density of 0.772 kg/DM³ (ASTM D4052). Itcorresponds to the product used in the examples hereinbelow.

For purposes of the present invention it is to be understood that asupplementary combustible liquid component useful in the presentinvention can be generally understood by those skilled in the art toinclude a broad range of petroleum distillate materials as well assupplementary combustible liquids from other sources, for example, plantor vegetable sources. Useful products generally boil in the range ofabout 145° C. to about 200° C. Turpentine is a supplementary combustiblefluid that could be used. Specifications for “gum spirit of turpentine”(natural, organic or vegetable-based turpentine) have been published byseveral national bodies including the American Society for Testing andMaterials (ASTM D 13-92) and the Bureau of Indian Standards (IS533:1973). These standards were devised largely for the qualityassessment of turpentine intended for use as a solvent, i.e., in wholeform rather than as a chemical feedstock in which the composition is ofprime importance. They generally specify parameters such as relativedensity or specific gravity, refractive index, distillation andevaporation residues. The International organization for Standardization(ISO), which is a world-wide federation of national standard institutes,has issued a standard, the main requirements of which are shown in thefollowing Table. A draft ISO standard for “oil of turpentine, Portugaltype, Pinus pinaster (1994)” includes physical data very similar to thatin the following Table, but with the addition of a range for opticalrotation (20° C.) of −28° to −35°. Compositional ranges are also givenfor a number of constituents of the turpentine including alpha-pinene(72-85%) and beta-pinene (12-20%).

TABLE Physical Property Requirements for Gum Spirit of Turpentine (ISOSpecification 412-1976) Property Value Relative density (20/20° C.)0.862-0.872 Refractive index (20° C., D line) 1.465-1.478 Distillation(% v/v) max 1 below 150° C.; min 87 below 170° C. Evaporation residue (%m/m) max 2.5 Residue after polymerization (% v/v) max 12 Acid value max1 Flash point (° C.) Min 32

“Turpentine substitute” is a “mineral oil” based replacement for thevegetable-based organic solvent turpentine and it is suitable for useherein. It is a hydrotreated light distillate of petroleum, which formsa clear transparent liquid at ambient or room temperature. It is acomplex mixture of highly refined hydrocarbon distillates mainly in theC9-C16 range. The liquid is highly volatile and the vapours areflammable. It is a widely available as a less costly substitute forturpentine. It is commonly used as an organic solvent in painting anddecorating, for thinning oil based paint and cleaning brushes. Alsoknown as turps substitute, mineral turpentine, or simply turps, whichcan cause confusion with vegetable-based turpentine.

White spirit, also known as Stoddard solvent is also suitable for useherein. It is a paraffin-derived clear, transparent liquid which is acommon organic solvent used in painting and decorating. It is a mixtureof saturated aliphatic and alicyclic C7 to C12 hydrocarbons with amaximum content of 25% of C7 to C12 alkyl aromatic hydrocarbons. Whitespirit typically is used as an extraction solvent, as a cleaningsolvent, as a degreasing solvent and as a solvent in aerosols, paints,wood preservatives, lacquers, varnishes, and asphalt products. Inwestern Europe about 60% of the total white spirit consumption is usedin paints, lacquers and varnishes. White spirit is the most widely usedsolvent in the paint industry.

Three different types and three different grades of white spirit areavailable. The type refers to whether the solvent has been subjected tohydrodesulfurization (removal of sulfur) alone (Type 1), solventextraction (Type 2) or hydrogenation (Type 3). Each type comprises threedifferent grades: low flash grade, regular grade, and high flash grade.The grade is determined by the crude oil used as the starting materialand the conditions of distillation. In addition there is Type 0, whichis referred to as distillation fraction with no further treatment,comprising predominantly saturated C9 to C12 hydrocarbons with a boilingrange of 140-200° C.

The physical properties of the three types of white spirit are shown inthe following table:

T1: Low T2: T3: High Property flash Regular flash Initial boiling point(IBP) 130-144 145-174 175-200 (° C.) Final boiling point (° C.) IBP +21, max. 220 Average relative molecular 140 150 160 mass Relativedensity (15° C.) 0.765 0.780 0.795 Flash point (° C.) 21-30 31-54 >55Vapor pressure (kPa, 20° C.) 1.4 0.6 0.1 Volatility (n-butyl 0.47 0.150.04 acetate = 1) Autoignition temperature 240 240 230 (° C.) Explosionlimits (% by 0.6-6.5 0.6-6.5 0.6-8   volume in air) Vapor density (air= 1) 4.5-5   4.5-5   4.5-5   Refractive index (at 20° C.) 1.41-1.441.41-1.44 1.41-1.44 Viscosity (cps, 25° C.) 0.74-1.65 0.74-1.650.74-1.65 Solubility (% by weight in <0.1 <0.1 <0.1 water) Kauri-butanolvalue 29-33 29-33 29-33 Aniline point (° C.) 60-75 60-75 60-75Reactivity reaction with strong oxidizing agents Odor threshold (mg/m3)— 0.5-5   4

The various fluids identified as “mineral spirits” are suitable for useas a supplementary combustible fluid in the present invention. Mineralspirits is commonly used as a paint thinner and mild solvent and it issuitable for use herein. In Europe, it is referred to as petroleumspirit They are especially effective in removing oils, greases, carbonand other material from metal. Mineral spirits is derived from the lightdistillate fractions during crude oil refining and comprise C6 to C11compounds, with the majority being C9 to C11. There are many differentsubstances generally referred to as mineral spirits and each generallyhas a different CAS number. One common type is mineral oil spiritsidentified as CAS 64475-85-0. Stoddard solvent, referred to above is aparticular type, subcategory or subset of mineral spirits, identified asCAS 8052-41-3 and contains 30-62 wt % alkanes, 27-40 wt % cycloalkanes,0.3-20 wt % alkylbenzenes, 0.007-0.1 wt % other benzenes, 0.2 wt %naphthalenes and 0.3 wt % acenaphthalenes. Commercial Stoddard Solventproducts are available under the tradenames Varsol 1 and Texsolve S.Similarly, benzine is another, subset of mineral spirits comprising C5to C9 hydrocarbons and boiling at about 154° C. to about 204° C. Mineralspirits on the other hand comprise 20-65 wt % alkanes, 15-40 wt %cycloalkanes and 10-30 wt % aromatics; the specific amount of eachvarying depending on the particular “mineral spirit” being considered.General properties for mineral spirits include vapor pressure of 2.53mmHg; API gravity of about 48 to about 51; density of about 0.793 at 15°C. and about 0.779 at 20° C.; kinematic viscosity of 1.43 cSt (ormm2/sec) at 15° C. and 1.78 cSt at 0° C.

Another supplementary combustible liquid that can be used is kerosene.Kerosene is typically defined as a refined petroleum solvent(predominantly C₉-C₁₆ hydrocarbon, which is typically a mixture of 25%normal paraffins, 11% branched paraffins, 30% monocycloparraffins, 12%dicycloparaffins, 1% tricycloparrafins, 16% mononuclear aromatics and 5%dinuclear aromatics. (NIOSH Pocket Guide, www.cdc.gov) Alternatively, aproduct known as hydrotreated kerosene (CAS No. 64742-47-8) can be used.As its name suggests, it is derived from kerosene, or straight runkerosene, by hydrogenation in order to saturate the double bonds presentin various molecules of kerosene. Its physical properties are not unlikekerosene. Common physical properties and other characteristics are shownin the following table.

Physical properties and descriptive information*

Property Value CAS number: 8008-20-6 molecular weight: 170(approximately, C₉ to C₁₆ hydrocarbons) melting point: −51° C. boilingpoint: 175-325° C. appearance: colorless to pale straw density: about0.8 g/mL specific gravity 0.95 (30° C.) kinematic viscosity 2.7 cSt (20°C.) odor: Odorless flash point: 65-85° C. molecular formula: C₉ to C₁₆hydrocarbons and others synonyms: kerosine; coal oil; fuel oil no. 1;range oil solubility: Insoluble in water, miscible in all petroleumsolvents structural composition varies greatly and composition: includesC₉ to C₁₆ hydrocarbons (aliphatic and aromatic) with a boiling range ofabout 175 to 325° C.Sources: Budavari, S. Ed, The Merck Index, 12th edition Merck & Co.Inc., Rahway, N.J., 1997, p 903; MSDS: Brown oil,www.brownoil.com/msdskerosene.htm;www.engineeringtoolbox.com/kinematic-viscosity-d_(—)397.html

In one embodiment an additive composition of the present inventioncomprises at least one alcohol and at least one surfactant or emulsifierand, optionally, a low viscosity, low density supplementary combustibleliquid, such as paint thinner as well as other components describedherein. The various embodiments of the fuel compositions of the presentinvention are generally prepared according to the methods describedherein. In one embodiment an additive composition, the components ofwhich are described herein, is added gradually to water, or vice versa,in order to prepare a mixture, preferably with mixing during theaddition, although mixing can be carried out after the components areadded to one another. Alternatively, the individual components of theadditive mixture and the water can be combined in any convenient orderprovided that a uniform mixture is obtained. Mixing is continued until asatisfactory distribution, dispersion or emulsion of components isachieved. Typically the additive composition is used in an amount ofabout 20% by weight based on the amount of the vegetable oil that willbe present in the final mixture. The amount of additive used can besuitably varied. Typically, the additive is used at about 2 wt % toabout 30 wt % based on the weight of the oil present; preferably about20 wt % to about 28 wt %; more preferably about 10 wt % to about 30 wt %for engines and about 10 wt % to about 20 wt % for burners and heaters.Furthermore, higher amounts of the additive can be used, for example,about 35 wt % or about 40 wt % or up to about 45 wt %, keeping cost inmind so that a suitable amount is used to achieve the desired effect andat a cost consistent with economic requirements. Alternatively, usefulamounts may include specific concentrations of about 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29 and 30 wt % or more, as well as ranges of values based onany two of the individual values recited; for example, 2-30%, 5-25%,etc. In this embodiment the additive is used in an amount sufficient toobtain a substantially complete emulsion of water and oil present in thecomposition. The mixture comprising water and additive is added to anoil or a fat of vegetable origin, for example, colza or canola oil. Theweight ratio of water to oil typically can be varied over a range andstill be useful in the present invention, for example, from about 4:1 toabout 1:4; a preferred ratio of water to oil is about 3:1 to about 1:3;more preferably about 2:1 to about 1:2; still more preferably about 1:1.Mixing of the water-additive combination with the vegetable oil iscontinued until a substantially complete, or suitable, emulsion of thecomponents is obtained.

Cetane number or CN is to diesel fuel what octane rating is to gasoline,it is generally recognized as a measure of the fuel's combustionquality. Cetane is an alkane molecule, specifically C₁₆H₃₄, that ignitesvery easily under compression, so it is assigned a cetane number of 100.All other hydrocarbons in diesel fuel, as well as other fuels intendedfor use in diesel engines, including biodiesel and the biofuelcompositions of the present invention, are indexed to cetane as anindicator of how well they ignite under compression. The cetane numbertherefore measures how quickly the fuel starts to burn (auto-ignites)under a standardized set of diesel engine conditions. Typicalhydrocarbon-based diesel fuel contains many hydrocarbon compounds andthere can be more than one compound susceptible to ignition in otherfuels, including the fuels of the present invention. Since eachcomponent can exhibit a different cetane number or modify the centanenumber of the fuel of which it is a component, the overall cetane numberof the fuel is an indicator of the average cetane quality of all of thecomponents present. A fuel with a high cetane number starts to burnshortly after it is injected into the cylinder; it has a short ignitiondelay period. Conversely, a fuel with a low cetane number resistsauto-ignition and has a longer ignition delay period. A typical dieselengine has acceptable performance with a fuel having a CN between about45 to about 50. Typically, there is no performance or emission advantagewhen the CN is greater than about 50; after this point, the fuel'sperformance reaches a plateau. Hydrocarbon diesel fuel sold commerciallyis said to be available in two CN ranges: 40-46 for regular diesel, and45-50 for premium. In addition to a higher CN, premium diesel includesadditives to improve the effective CN and lubricity of the fuel as wellas detergents to clean the fuel injectors and minimize carbon deposits,water dispersants (since water in hydrocarbon diesel fuel is consideredobjectionable), and other additives depending on geographical andseasonal needs. Cetane number can be determined using standardizedtests, including ASTM D613 and EN ISO 5165. The cetane number rating inthis test compares the diesel fuel's performance in a standard enginewith that of a mixture of cetane and alpha-methyl-naphthalene. Thecetane number is the percentage by volume of cetane in the mixture thathas the same performance as the fuel being tested. Suitable fuelstypically will have CN values of at least about 35 to about 55;preferably about 40 to about 50; more preferably about 45 to about 50;for example at least about 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 or 55.Alternatively, cetane number can be estimated by calculating the valueaccording to the procedures specified in ASTM D976, using the density ofthe fuel and its mid-distillation temperature, or in ASTM D4737 using afour variable equation. When an estimated cetane number is determined inthis manner, it is sometimes referred to as cetane index to distinguishit from the value determined according to the engine test, as in ASTM613. It is understood by those skilled in the art that where a cetaneindex is calculated, the value is dependent on the fuel properties andis not affected by additives that may be included to improve cetanenumber. Such additives will, of course, affect the cetane numberdetermined by use of an engine test since the overall fuel compositionaffects the value measured in that test. Cetane index values can also beuseful for characterizing a fuel composition of the present invention.When used, a cetane number improving additive or mixture of additivescan be present in an amount effective to improve the CN of the fuelcompositions of the present invention to the extent desired; in otherwords, to a level suitable for the particular application or use towhich the emulsified vegetable fuel will be put. In one embodiment, theconcentration of the cetane improver is at a level of up to about 10% byweight; in another embodiment about 0.05 to about 10% by weight; in afurther embodiment about 0.05 to about 5% by weight; in a still furtherembodiment about 0.05 to about 1% by weight; alternatively, about 0.1 toabout 1% by weight.

Various chemical compounds have been identified that have the ability toimprove the cetane number of diesel fuel. Where necessary or desired tomeet specific performance requirements in certain applications, oneembodiment of the vegetable oil-based water-fuel emulsion compositionsof the present invention can optionally include one or more compoundshaving the ability to increase cetane number. Useful cetane improversinclude but are not limited to one or more of peroxides, nitrates,nitrites, nitrocarbamates, mixtures thereof and the like. Useful cetaneimprovers include but are not limited to nitropropane, dinitropropane,tetranitromethane, 2-nitro-2-methyl-1-butanol,2-methyl-2-nitro-1-propanol, and the like. Also included are nitrateesters of substituted or unsubstituted aliphatic or cycloaliphaticalcohols which may be monohydric or polyhydric. These compounds includesubstituted and unsubstituted alkyl or cycloalkyl nitrates having up toabout 10 carbon atoms, and in one embodiment about 2 to about 10 carbonatoms. The alkyl group may be either linear or branched, or a mixture oflinear or branched alkyl groups. Examples of such compounds includemethyl nitrate, ethyl nitrate, n-propyl nitrate, isopropyl nitrate,allyl nitrate, n-butyl nitrate, isobutyl nitrate, sec-butyl nitrate,tert-butyl nitrate, n-amyl nitrate, isoamyl nitrate, 2-amyl nitrate,3-amyl nitrate, tert-amyl nitrate, n-hexyl nitrate, n-heptyl nitrate,n-octyl nitrate, 2-ethylhexyl nitrate, sec-octyl nitrate, n-nonylnitrate, n-decyl nitrate, cyclopentyl nitrate, cyclohexyl nitrate,methylcyclohexyl nitrate, and isopropylcyclohexyl nitrate. Also usefulare the nitrate esters of alkoxy-substituted aliphatic alcohols such as2-ethoxyethyl nitrate, 2-(2-ethoxy-ethoxy) ethyl nitrate,1-methoxypropyl-2-nitrate, 4-ethoxybutyl nitrate, etc., as well as diolnitrates such as 1,6-hexamethylene dinitrate. A useful cetane improveris 2-ethylhexyl nitrate.

Organic peroxides can also be useful as cetane improvers in the fuelcompositions herein. Generally useful compounds are dialkyl peroxides ofthe formula R1OOR2 wherein R1 and R2 are the same or different alkylgroups having 1 to about 10 carbon atoms. Suitable peroxide cetaneimprover compounds should be soluble in the fuel composition andthermally stable at typical fuel temperatures of operating engines.Peroxides wherein R1 and R2 are tertiary alkyl groups having about 4 orabout 5 carbon atoms are especially useful. Examples of suitableperoxides include di-tertiary butyl peroxide, di-tertiary amyl peroxide,diethyl peroxide, di-n-propyl peroxide, di-n-butyl peroxide, methylethyl peroxide, methyl-t-butyl peroxide, ethyl-t-butyl peroxide,propyl-t-amyl peroxide, mixtures thereof and the like. Preferredperoxides generally exhibit one or more and preferably most of thefollowing characteristics: good solubility in the fuel, suitable waterpartition coefficient characteristics, good thermal stability andhandling characteristics, have no impact on fuel quality or fuel systemcomponents, and have low toxicity. A useful peroxide is di-tertiarybutyl peroxide, also sometimes referred to as tertiary butyl peroxide.

The biofuel of the present invention typically has a density suitablefor its use as a fuel in diesel engines and in other applications wherediesel fuel would otherwise be useful, including in furnaces, gas orcombustion turbines and other combustion equipment. Density can bemeasured according to the standard test method, EN ISO 3675, at 15° C.and suitable fuels have a density of about 850 kg/m³ to about 950 kg/m³;preferably about 860 kg/m³ to about 910 kg/m³; for example about 870kg/m³ to about 890 kg/m³. Alternatively, in the United States, dieselfuel density is characterized by the standard developed by the AmericanPetroleum Institute, referred to as API gravity. Typical API gravityvalues for fuels of the present invention useful as fuels for dieselengines range from about 25 API to about 40 API, corresponding tospecific gravity values of about 0.904 to about 0.825 (at 60° F. or15.6° C.); preferably about 26 API gravity to about 38 API gravity; morepreferably about 27 API gravity to about 37 API gravity; for example,about 35 API gravity, corresponding to a specific gravity of about0.850. The accepted formula relating API gravity to specific gravity is:API=(141.5/Sp.Gr.)−131.5 (with the abbreviation Sp.Gr. meaning specificgravity and wherein it is determined at 60° F. or 15.6° C., as notedabove.

Biofuel compositions of the present invention typically have a viscosityso that they are suitable for use as a fuel in diesel engines and inother applications where diesel fuel would otherwise be useful,including furnaces and other combustion equipment. Viscosity can bemeasured according to the standard test methods, EN ISO 3104 or ASTMD445 (kinematic viscosity at 40° C.), wherein potentially useful valuescan be about 3 mm²/s to about 60 mm²/s; alternatively about 3.5 mm²/s toabout 50 mm²/s; or for example about 3.6 mm²/s to about 40 mm²/s; about3 mm²/s to about 40 mm²/s; about 3 mm²/s to about 30 mm²/s; about 1mm²/s to about 25 mm²/s; about 2 mm²/s to about 12 mm²/s; about 3 mm²/sto about 10 mm²/s; about 4 mm²/s to about 8 mm²/s; about 2 mm²/s toabout 6 mm²/s; and including viscosity values that, upon testing aresuitable for use in the application or environment of a suitable biofuelcomposition.

Other suitable optional ingredients can be included in the compositionsof the present invention provided that they do not substantiallyadversely affect performance of the composition and its intended use.Included in the category of such other optional ingredients would be,for example, thermal and aging stabilizers; coloring agents, dyes andmarkers, particularly those permitted in the European Union as set forthin EN 14214:2003-5.1; agents to modify the odor of the mixture in orderto prevent inadvertent ingestion, including, for example, alkyds; etc.Alternatively, and if necessary, agents can be added in a suitableamount, typically at a low concentration, that are capable of modifyingor masking an unpleasant odor or smell, if any, of the exhausted gasafter combustion. Other conventional additives and blending agents forfuel compositions of the present invention may be present. For example,the fuels of this invention may contain conventional quantities of suchconventional additives as rust inhibitors such as alkylated succinicacids and anhydrides, inhibitors of gum formation, metal deactivators,upper cylinder lubricants, friction modifiers, detergents, antioxidants,heat stabilizers, bacteriostatic agents, microbiocides, fungicides andthe like. Such conventional additives can be present in the fuelcomposition at concentrations of up to about 1 wt % based on the totalweight of the water-vegetable oil fuel emulsion; for example about 0.01wt % to about 1 wt %.

The practice of the present invention, including in particular the abovedescribed additive composition, results in the preparation of a fuelcomposition based on animal or. vegetable fats or oils and water in anemulsion that is stable for an extended time and over a wide range oftemperatures, for example about −10° C. to about +50° C. Furthermore, ina test conducted at −25° C., a composition of the present invention, forexample compositions as shown in Examples 1 and 2, including paintthinner and 30 grams of cetyl alcohol, did not exhibit any evidence offreezing, cloudiness or phase separation. The fuel produced according tothe compositions and methods of the present invention can be usedwithout modification to the tanks and/or piping systems of the motorsand burners in common use. Thus another advantage of the presentinvention is that it permits the return at any moment to the use oftraditional fuels without modification of the systems in which the fuelis used.

Further advantages can be realized with certain preferred methods andcompositions of the present invention, including:

(a) Product and manufacturing costs are low and competitive with otherfuels, particularly due to the presence of water in the composition;

(b) The present compositions do not exhibit the high solvent power ofmethyl esters that are present in traditional biodiesel, which can causeproblems with polymeric materials present in the storage systems,burners and engines, including linings, packing rings and seals;

(c) The fuel of the present invention does not leave deposits in thestorage tanks and fuel lines, thus reducing the need for frequentmaintenance;

(d) The fuel of the invention is renewable since it is based onvegetable and animal products that can be regularly replaced.Furthermore, not only is the energy source renewable, but the amount ofcarbon dioxide emitted during combustion corresponds very closely to theamount of carbon dioxide used by the plants in generating the vegetablematter which is the source of the oils or fats. This, of course, cannotoccur in the case of petroleum based fuels;

(e) Emission of nitrogen oxides, particularly undesirable pollutants, isreduced with respect to traditional biodiesel-based fuels, especially inview of the water and additive mixture. In a test using a diesel engineoperating at 1500 rpm, traditional biodiesel produced 196 mg/Nm³,whereas a composition of the present invention under the same conditionsresulted in 160 mg/Nm³, more than an 18% reduction (where Nm³ refers to“normal” cubic meters, defined as volume at temperature T=20.0° C. (68°F.), and pressure P=1.01 bar (14.72 psia);

(f) Incombustible hydrocarbons produced during the combustion of a fuelcomposition of the present invention are less than those produced bytraditional biodiesel-based fuels and CO emissions and are believedtypically to be about 15%-20% less. In a test of a fuel compositionsimilar to that shown in Example 1 (including 30 grams of cetyl alcohol,but without paint solvent) in a diesel engine operating at 1500 rpm, COemissions were observed to be reduced by 37 wt % (838 versus 1248mg/Nm³;

(g) The chemical composition and average size of particulate matterresulting from combustion of traditional biodiesel-based fuels and thefuels of the present invention are subject to variability. Limitedtesting for smoke has been conducted using the Bacharach Scale (values 0to 9, with 0 indicating the lowest level) and employing the ZambelliEmicont 50 test instrument and a 3 meter long exhaust pipe connected toa diesel engine (the Bacharach scale may also be referred to in testmethod ASTM D 2156 which measures smoke density in flue gasses fromburning petroleum distillate heating fuels). A comparative value of 6was observed using a fuel composition of the present invention asdescribed in subparagraph (f) above. While particulate matter generatedduring combustion of traditional biodiesel based fuels is thought toserve a useful function by absorbing some of the undesirable andpolluting aromatic compounds produced during combustion of that fuel,the fuel of the present invention is believed to produce very little ofsuch aromatic compounds in the first place. Moreover, it has been foundthat particulate matter produced during combustion of the fuel of thepresent invention is up to about 70% less than that produced bypetroleum-based fuels and are, on average, larger than those produced bysuch petroleum-based fuels. Additionally, it is generally believed thatlarger particles are less dangerous since they are less likely to bepermanently retained in the lungs than smaller particles. Particulates,measured according to UNICHIM 494 (Association for Unification in theField of the Chemical Industry, a standards setting organization inItaly) resulted in 0.16 mg/Nm³, well below the levels observed withgasoil (0.30 mg/Nm³) and biodiesel (0.24 mg/Nm³).

(h) Emission of SO₂ does not constitute a problem for the fuels of thepresent invention since there is no sulfur present in the vegetable oilor fat and the amount and type of other components present can becontrolled in order to limit, reduce or eliminate the presence of sulfur(as well as nitrogen).

(j) It has been observed that the biofuel compositions of the presentinvention exhibit anti-microbial, anti-bacterial and anti-moldcharacteristics, especially compositions comprising hydrogenated castoroil and/or cetyl alcohol as well as ethanol. Three different tests wereperformed, one each against bacteria, spores and mould/fungi, to confirmthis activity of the novel, formulated biofuel of Example 1, containing30 grams hydrogenated castor oil and 500 grams paint solvent and Example2, containing 25 grams cetyl alcohol. The biofuel compositions exhibitedsuccessful results in the following tests:

Test for activity against spores: Successful disinfection according tothe British Standard (BS EN 1276) occurs when there is a five logreduction in cell number within 5 minutes, meaning that the reduction ofspore number must be at least of 95% in an assigned period of time.Based on this, the biofuel composition was tested against germs (spores)of the following strains: Mycobacterium smegmatis and BacillusStearothermophilus.

Test for activity against fungi: The tests against mold and fungifollowed the guidelines of the European standard 1275 that requires aminimum of a four log reduction in cell number within five minutes. Thestrain used was Candida albicans, strain ATCC number 10231.

Biofuel compositions made according the methods and componentspreviously described include those useful, for example, in multi-jet newgeneration diesel engines as well as traditional diesel engines. Suchcompositions can comprise for example, about 25 to about 30 wt % water,about 40 to about 60 wt % vegetable oil and about 15 to about 30 wt %additive.

The following aspects of the invention represent possible alternativeembodiments:

-   1. A fuel mixture prepared from the following components: (A) 1500    parts vegetable oil or fat; and (B) 900 parts water; and (C) 400    parts denatured ethanol 90 wt % (180 proof); and, (D) 30 parts of at    least one component selected from the group consisting of (1)    hydrogenated castor oil; (2) cetyl alcohol; and (3) a mixture of (1)    and (2).-   2. The fuel mixture of aspect 1 further comprising 500 parts of    odorless paint solvent.-   3. A fuel mixture prepared from the following components: (A) 1500    parts vegetable oil or fat; and (B) 900 parts water; and (C) 400    parts denatured ethanol 90 wt % (180 proof); and, (D) 30 parts of at    least one component selected from the group consisting of (1)    hydrogenated castor oil; (2) cetyl alcohol; and (3) a mixture of (1)    and (2) according to the following method: (I) components (C)    and (D) are mixed with one another to form an additive; (II) the    additive is mixed with component (B) to form a mixture (II); (III)    mixture (II) is added with concurrent mixing, at a suitable rate    to (A) in order to produce a substantially emulsified mixture.-   4. A fuel additive comprising a mixture of: (A) 400 parts denatured    ethanol 90 wt % (180 proof); and, (B) 30 parts of at least one    component selected from the group consisting of (1) hydrogenated    castor oil; (2) cetyl alcohol; and (3) a mixture of (1) and (2).

The following examples are provided as specific illustrations ofembodiments of the claimed invention. It should be understood, however,that the invention is not limited to the specific details set forth inthe examples. All parts and percentages in the examples, as well as inthe specification, are by weight unless otherwise specified.Furthermore, any range of numbers recited in the specification orclaims, such as that representing a particular set of properties, unitsof measure, conditions, physical states or percentages, is intended toliterally incorporate expressly herein by reference or otherwise, anynumber falling within such range, including any subset of numbers withinany range so recited. For example, whenever a numerical range with alower limit, R_(L), and an upper limit R_(U), is disclosed, any number Rfalling within the range is specifically disclosed. In particular, thefollowing numbers R within the range are specifically disclosed:R=R_(L)+k(R_(U)−R_(L)), where k is a variable ranging from 1% to 100%with a 1% increment, e.g., k is 1%, 2%, 3%, 4%, 5%. . . . 50%, 51%, 52%.. . . 95%, 96%, 97%, 98%, 99%, or 100%. Moreover, any numerical rangerepresented by any two values of R, as calculated above is alsospecifically disclosed.

For purposes of the present invention, unless otherwise defined withrespect to a specific property, characteristic or variable, the term“substantially” as applied to any criteria, such as a property,characteristic or variable, means to meet the stated criteria in suchmeasure such that one skilled in the art would understand that thebenefit to be achieved, or the condition or property value desired ismet.

Throughout the entire specification, including the claims, the word“comprise” and variations of the word, such as “comprising” and“comprises,” as well as “have,” “having,” “includes,” “include” and“including,” and variations thereof, means that the named steps,elements or materials to which it refers are essential, but other steps,elements or materials may be added and still form a construct within thescope of the claim or disclosure. When recited in describing theinvention and in a claim, it means that the invention and what isclaimed is considered to be what follows and potentially more. Theseterms, particularly when applied to claims, are inclusive or open-endedand do not exclude additional, unrecited elements or methods steps.

As used throughout the specification, including the describedembodiments, the singular forms “a,” an,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to “a surfactant” includes a single surfactant aswell a two or more different surfactants in combination, reference to “avegetable oil or fat” includes mixtures of two or more vegetable oils orfats as well as a single vegetable oil or fat, and the like.

The term “about” encompasses greater and lesser values than thosespecifically recited provided that the value of the relevant property orcondition facilitates reasonably meeting the technologic objective(s) ofthe present invention as described in detail in the specification andclaims. More specifically, the term “about” when used as a modifier for,or in conjunction with, a variable, is intended to convey that thenumbers and ranges disclosed herein are flexible and that practice ofthe present invention by those skilled in the art using, for example,concentrations, amounts, contents, carbon numbers, temperatures,properties such as density, purity, etc., that are outside of a statedrange or different from a single value, will achieve the desired result,namely, a biofuel additive composition or a fuel composition or mixturecomprising such an additive.

Examples Example 1 New Generation Hi-Pressure Injection Diesel

A fuel mixture is prepared from the following components:

-   -   1500 grams vegetable oil or fat; and    -   900 grams water (e.g., tap water); and    -   400 grams denatured ethanol 90° (180 proof); and,    -   (a) 30 grams hydrogenated oil of ricin (castor oil);    -   alternatively, a mixture using (b) 30 grams cetalol (cetyl        alcohol) is prepared; and (c) a further alternative mixture        using (a)+(b) together (30 grams total) is also prepared; and        optionally,    -   500 grams odorless paint solvent is also included in one or more        of the above described mixtures.

The mixture is suitable for use with a new generation high pressureinjection diesel engine. Based on current raw material costs it isestimated that the above composition costs about 204 ε/1000L (about$0.94/gal at current exchange rates). It is expected that the cost forproducing the composition on a commercial scale will be lower. Forcomparison purposes, the raw material cost of commercial biodiesel fuelis about 492 ε/1000L (about $2.26/gal at current exchange rates).

Example 2 Traditional Tractor-Type Low-Pressure Injection Diesel

A fuel mixture is prepared from the following components:

-   -   1100 grams vegetable oil; and    -   500 grams water; and    -   250 grams ethyl alcohol (180 proof); and    -   25 grams hydrogenated castor oil; or cetalol (cetyl alcohol); or        mixture of castor oil and cetalol; and    -   25 grams paint thinner.

The mixture is suitable for use with a traditional tractor-typelow-pressure injection diesel engine. Based on current raw materialcosts it is estimated that the above composition costs about 243 ε/1000L(about $1.12/gal at current exchange rates). It is expected that thecost for producing the composition on a commercial scale will be lower.

Example 3 Modified Traditional Tractor-Type Low-Pressure InjectionDiesel

A fuel mixture is prepared from the following components:

-   -   1100 grams vegetable oil;    -   900 grams water;    -   250 grams ethyl alcohol (180 proof);    -   25 grams (a) hydrogenated castor oil; or (b) cetalol or a        mixture of (a) and (b);    -   300 grams odorless paint thinner.

The mixture is suitable for use with a modified traditional tractor-typelow pressure injection diesel engine.

Example 4 Fuel for Use in Oil Burners

A fuel mixture is prepared from the following components:

-   -   900 grams oil;    -   500 grams water;    -   25 grams (a) castor oil; or (b) cetalol; or (c) a mixture of (a)        and (b);    -   250 grams ethyl alcohol.

The mixture is suitable for use in oil burners.

Example 5 Fuel for Use in Modified Oil Burners

A fuel mixture is prepared from the following components:

-   -   1100 grams oil;    -   900 grams water;    -   375 grams ethyl alcohol;    -   30 grams (a) hydrogenated castor oil; or (b) cetalol.

The mixture is suitable for use in modified oil burners.

Example 6

Fuel mixtures of the present invention were prepared as follows: thewater and ethanol were first mixed with one another. The vegetable oilwas then added slowly to the alcohol-water mixture with stirring andfinally the emulsifier or surfactant was added to the mixture containingthe oil. For the composition in which a cetane improver was used, thatcomponent was added to the mixture at the end. The mixtures were allprepared at about ambient or room temperature, 22° C. Correspondingmixtures have been prepared using ultrasonic mixing equipment, whichequipment particularly advantageous for preparing stable emulsionshaving a small particle size, for example less than about 5 microns onaverage (“Sonolator” ultrasonic homogenizing system, Sonic Corp.,Conn.). The compositions described herein are amenable to preparing suchemulsions, also referred to herein as microemulsions. The microemulsionscould also be prepared at 22° C. and at pressures of about 500 psi toabout 1500 psi, although pressures as high as 5000 psi also producedstable microemulsions. The fuel components and amounts are shown in thefollowing table:

Cetane Fuel Mixture Vegetable oil** Water Ethanol Emulsifier‡ additive*Biofuel 1  1200 g   335 g   105 g HCO: 5 g 72.95 wt % 20.36 wt %  6.38wt % 0.31 wt % Biofuel 2  1200 g   225 g   53 g HCO: 5 g   7 g 80.53 wt% 15.11 wt %  3.56 wt % 0.33 wt % 0.47 wt % Biofuel 3   900 g   350 g  250 g Tween: 15 g 59.40 wt % 23.10 wt % 16.50 wt % 1.00 wt % **Refinedsoybean oil ‡HCO = hydrogenated castor oil, 98% pure; Tween 80 *2-ethylhexyl nitrate

The above mixtures were tested for various properties and performancecharacteristics under different test conditions and using variousstandard fuels for comparison.

Specifically, Biofuel 3 was tested in a stationary burner and itsperformance compared to gas oil, biodiesel and BTZ fuel oil and wateremulsion mixture. Descriptions and properties of the reference fuels canbe found in a published report titled, “Sperimentazione CombustibiliAnalisi comparativa di combustibili per uso civile” (FuelExperimentation. Comparative analyses of fuels for civic use) Dec. 5,2005, by Stazione Sperimentale par i Combustibili (SSC) and ConsorzioIngengneria per l'Ambiente e lo Sviluppo Sosteniblile (IPASS); andreported at http://www.ssc.it/, incorporated herein by reference.Biofuel 3 was tested using an experimental thermal plant consisting of areversed flame Ravasio Model TRM 150 boiler with a nominal thermalcapacity of 175 kW and a Elco Klockner Model EK 3.50 S-Z burner for fueloil. Heat generated is discharged to a heat exchanger for measurement ofperformance and exhaust gasses are also analyzed for emissions. Thefollowing conditions were used: fuel tank temperature about 16° C.;burner warm-up temperature about 60° C.; atomization pressure, 28 bar;fuel feed, 23 kg/h; thermal power, 160 kW; excess oxygen in exhaust, 6%.BTZ fuel oil was blended with water at 13 wt % and it was blended withbiodiesel (standard mixture of fatty acid methyl esters) at 20 wt %.Test results are reported in the following table.

Test Results

Fuel Tests* BTZ BTZ + Water BTZ + Biodiesel Biofuel 3 PM, mg/Nm3 21.110.0 11.1 13.4 PM10, mg/Nm3 20.9 10.0 11.1 10.8 NOx, mg/A/m3 560.4 469.3543.7 122 CO, mg/Nm3 10.7 37.7 10.5 138 UHC, mg/Nm3 <0.4 0.9 <0.4 17.5Organics 2 Formaldehyde, 20 10 30 6.44 μg/Nm3 Acetaldehyde, 20 60 — 1.93pg/Nm3 Propionaldehyde, — — — 0.41 pg/Nm3 Combustion 93.4 94.4 92.8 92Yield, % *Abbreviations and tests: PM = total particulate matter, UNI13284-1; PM10 = fine particulates, <10 μM, EPA 201A; NOx, nitrogenoxides, UNI 10878; CO, carbon monoxide, UNI 9969; UHC = unburnedhydrocarbons, UNI EN 12619; Organics, SSC test method; combustion yieldor energy efficiency, UNI 10389.In other laboratory tests Biofuel 3 exhibited an excellent flow point of−42° C. (measured according to ISO 3016-94) as well as viscosity andlower heating capacity values (ASTM D 240-02) typical of the class offuel oils. As shown above, Biofuel 3 also resulted in low NOx and otheremissions. It was also observed that Biofuel 3 exhibited a regular,stable, deep yellow flame at the burner. An increase in density of therecirculated fuel was observed, which response can probably be mitigatedby further improvements in emulsion particle size as well as adjustmentsto the composition, according to the methods described above.

Heat capacity and low temperature characteristics of Biofuel 2 andBiofuel 3 were measured using standard thermogravimetric analysis (TGA)and the new technique of modulated differential scanning calorimetry(MTDSC). For TGA a heating rate of 10° C./min is used until 100° C.,after which the sample is heated isothermally for one hour and then thesame heating rate is resumed until 1000° C., after which the sample isthoroughly degraded. MTDSC superimposes a sinusoidal heating wave (±0.5°C., 60 sec. period) on the normally linear ramp (5° C./min.);temperature interval −20° C. to +250° C. in an inert nitrogenatmosphere. The heating tests reflected the stability of theemulsifier(s) since the solvents and water are evaporated at 100° C. Thelaboratory test showed that Biofuel 1 was stable until 200° C. whereasBiofuel 2 was stable until about 165° C. Heat capacity (J/g*° C.) wasabout 1.6 for Biofuel 1 and about 1.8 for Biofuel 2, similar to that ofgas oil. Furthermore, both Biofuel 1 and Biofuel 2 did not exhibitthermal effects or freezing at −20° C.

Further testing was conducted at the “Centro Universitario di Ricercaper lo Sviluppo sostenibile” near Rome, Italy (University Center forResearch and Sustainable Development, CIRPS). Biofuel 1 and Biofuel 2were tested and compared to traditional diesel fuel for powerperformance and emissions using two different automobile engines, FiatMultipla 1.9 jtd (common rail engine) and Fiat Punto 1.7 td (aspiratedengine, also called Fiat Punto TD 70 ELX). Power tests were performedusing a dynamometer, Cartec LPS 2510, with the following results:

Torque Test Fuel Type Vehicle Power (kW) (Nm) 1 Diesel Multipla 84.3 2152 Biofuel 1 ″ 71.7 160 3 Biofuel 2 ″ 81.5 209 4 Diesel Punto 47.7 123 5Biofuel 1 ″ 42.5 117 6 Biofuel 2 ″ 45.8 127Compared to traditional diesel, in the Fiat Multipla power decreasedabout 3% with Biofuel 1 and about 15% with Biofuel 2. In the Fiat Punto,the power decreased about 4% with Biofuel 2 and about 11% with Biofuel 1compared to traditional diesel. However, it has also been reported thatwhen traditional biodiesel is compared to traditional diesel powerdecreases about 11%. (Energy Information Administration,www.eia.doe.gov/oiaf/analysispaper/biodiesel).

Emissions tests were conducted with Biofuel 2 using the same vehiclesaccording to the various standards and criteria of UNICHIM 422, 467 and494 methods; UNI 10169 regulation; and DM 25/08/00 for sulfur andnitrogen oxide measurements. The test results are summarized in thefollowing table:

Total Smoke Dispersed Index Temp. Carbon Bacharach Auto/Fuel ° C. O2 %CO ppm SOx ppm NOx ppm Mg/Nm3 Scale* Fiat Multipla Diesel 62 20.6 14751.1 35 160.3 6 Biofuel 2 62.5 20.6 123 <1 1 105.7 4 Fiat Punto Diesel57 18.4 330 57 36 157 6 Biofuel 2 54.3 18.4 313 <1 33 117 4 *Lowervalues indicate better performanceThe results of these tests indicate very good performance for Biofuel 2compared to traditional diesel fuel.

Example 7

A composition of the present invention, referred to as a biofuelcomposition, having components that provided a composition particularlyuseful in stationary burners or furnaces; for example, burners used forgenerating heat and power. The components are shown in the followingtable:

Biofuel 7A Amount, Amount, Useful Range, Component grams weight % weight% Vegetable Oil 900 63.649 55-70 Water 300 21.216 15-30 Ethyl Alcohol,95% 200 14.144  5-20 Emulsifier* 14 0.990 0.1-5   Total 1414 100.000100.000 *Polyoxyethylene(20) sorbitan monooleate (Tween 80)

The composition represented by Biofuel 7A was evaluated in severalstandard fuel tests. The tests and results are summarized in thefollowing table:

Test Method Result API Gravity@60° F. ASTM D4052 21.04 Deg. API SulfurASTM D4294 0.0206 Wt % Flash Point ASTM D93A 72° F. Sediment & WaterASTM D1796 0.05 Vol % Viscosity, Kin@100° F. ASTM D445 22.93 cSt CaronResidue 10% bottom ASTM D4530 <0.05 Wt % Sulfated Ash ASTM D874 <0.001Wt % Hydrogen ASTM D5291 12.27 Wt % Copper Corrosion ASTM D130 1a RatingTotal Acidity ASTM D664 0.040 mg KOH/g Stability (BS&W) ASTM D96 <0.1%Specific Gravity@60° F./60° F. AOCS Cc 10a-25 0.9341 Bomb CalorimetryASTM D240 11,900 BTU/lb Phosphorous ASTM D1091 3.4 ppm Sulfur ASTM D12918 ppm Cloud point (gel point) EN ISO 6245 −28° F. Potassium EPA 258.1<0.1 ppm Sodium EPA 273.1 <0.1 ppm Calcium EPA 215.1 3.6 ppm BTU/gal*92,600 *Calculated from density and bomb calorimetry data

Another biofuel composition particularly useful in vehicles, forexample, cars, trucks, farm equipment, etc., preferably having dieselengines or engines suitable for burning diesel fuels or theirequivalent, was also prepared according to the following formula:

Biofuel 7B Amount, Amount, Useful Component grams weight % RangeVegetable oil 1200 80.53 75-85% Water 225 15.11  5-20% Ethyl alcohol,95% 53 3.56 1-5% Emulsifier* 5 0.33 0.1-5   Cetane Improver** 7 0.470.1-1%   Total 1490 100.00 100.00 *mixture: 50 wt % Polyoxyethylene(20)sorbitan monooleate (Tween 80) + 50 wt % Sorbitan monolaurate (Span 20)**2-ethyl hexyl nitrate

Example 8

A further Biofuel composition of the present invention was prepared asfollows: the water and propylene glycol were first mixed with oneanother. Small amounts of the vegetable oil were then added slowly tothe alcohol-water mixture with stirring after each addition and finallythe emulsifier or surfactant was added to the mixture containing theoil. The mixture was prepared at about room temperature, 22° C.Alternatively the mixture was prepared using ultrasonic mixing equipmentalso as described above. However, using such equipment it was possibleto add all ingredients simultaneously and still obtain a stableemulsion, a microemulsion, having a small particle size, for exampleless than about 5 microns on average. As above, the microemulsion couldalso be prepared at 22° C. and at pressures of about 500 psi to about1500 psi, as well as pressures as high as 5000 psi. The fuel compositionof this example utilized components resulting in a compositionparticularly useful in applications requiring an elevated flashpointcompared to the compositions identified above, including but not limitedto uses such as diesel engines for vehicles and burners. The fuelcomponents are shown in the following table:

Biofuel 8 Amount, Useful Range, Component weight % weight % VegetableOil 66 55-75 Water 23.5 15-30 Propylene glycol 9.5  5-20 Emulsifier* 10.1-5   Total 100.000 100.000 *Polyoxyethylene(20) sorbitan monooleate(Tween 80)

The composition represented by Biofuel 8 was evaluated in severalstandard fuel tests. The tests and results are summarized in thefollowing table:

Test Method Result Units API Gravity @ 60° F. ASTM D4052 15.7 Deg. APISulfur ASTM D4294 0.0202 Wt % Flash Point ASTM D93 A 167-205 ° F.Sediment & Water ASTM D 1796 1-4 Vol % Viscosity, Kin @ 100° F. ASTMD445   11-52.4 cSt Carbon Residue 10% bottom ASTM D4530 <0.05 Wt %Sulfated Ash ASTM D 874 <0.001 Wt % Hydrogen ASTM D 5291 12.23 Wt %Copper Corrosion ASTM D130 1a Rating Total Acidity ASTM D664 0.039 mgKOH/g

Clearly, the flash point of Biofuel 8 is significantly higher than thatof Biofuel 7A. Furthermore, mixtures of up to 25 wt % Biofuel 8 withtraditional diesel fuel, biodiesel fuel and ethanol can be prepared andthe two fuel mixtures can be readily dispersed in one another and arestable, in other words they do not separate into different phases.

Example 9

In another experiment, adding 0.5 wt % of a cetane improver, 2-ethylhexyl nitrate, to the composition of Biofuel 8 produced a stable biofuelcomposition within the scope of the invention and exhibiting anincreased cetane number.

Example 10

Additional formulations were prepared and tested in order to evaluatestability of vegetable oil based emulsion compositions. The formulationsare shown in the table below:

Example 10- Component, wt % 1 2 3 Vegetable Oil 75.9 80 80 Water 18.5 44 Ethyl alcohol (95%) 4.5 14 14 Emulsifier(s)* 0.6 1 0.5 + 0.5 CetaneImprover** 0.5 1 1 Total 100.0 100.0 100.0 Emulsion Stability <0.1 5 NilWt %, (ASTM D96) *10-1 and 10-2: Polyoxyethylene(20) sorbitan monooleate(Tween 80); 10-3: mixture of Tween 80 and sorbitan monooleate (Span 80)**2-ethyl hexyl nitrateBased on the amount of sediment that could be separated, Example 10-1 inthe table above is characterized as a stable emulsion fuel whereasExample 10-2 is considered unstable. However, by utilizing a blend ofemulsifiers with an effective HLB of 9.6 ((0.5×14.9)+(0.5×4.3)) it waspossible to modify the properties of the composition sufficiently sothat a stable emulsified fuel could be obtained.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A biofuel composition comprising an aqueous emulsion having: (A) acontinuous phase comprising about 50 wt % to about 95 wt % of at leastone liquid oil of vegetable or animal origin or mixtures thereof; (B) awater-containing dispersed phase comprising about 1 wt % to about 50 wt% of water; (C) about 1 wt % to about 25 wt % of a hydroxyl-containingorganic compound selected from the group consisting of monohydric,dihydric, trihydric and polyhydric alcohols, provided that when amonohydric alcohol is present there is also present at least one oftert-butyl alcohol, at least one C2-C4 alkylene glycol or a mixture ofboth; (D) about 0.05 wt % to about 10 wt % of at least one emulsifier;wherein the dispersed phase comprises water-containing droplets havingan average particle size of less than about 20 microns and wherein allamounts are expressed based on the total weight of the composition. 2.The biofuel of claim 1 wherein the at least one emulsifier exhibits ahydrophilic-lipophilic balance, HLB, of about 8.5 to about
 18. 3. Thebiofuel of claim 2 wherein the at least one emulsifier is selected fromthe group consisting of polyethylene glycol-polypropylene glycol blockcopolymers, sorbitan monooleate, sorbitan monostearate, sorbitanmonopalmitate, sorbitan monolaurate, polyoxyethylene (20) sorbitantrioleate, polyethylene (20) sorbitan monooleate, polyethylene (20)sorbitan monolaurate, and mixtures thereof.
 4. The biofuel of claim 1further comprising an effective amount of an additive to increase thecetane number of the biofuel composition.
 5. The biofuel of claim 4wherein the cetane additive is selected from the group consisting ofperoxides, nitrates, nitrites, nitrocarbamates, and mixtures thereof. 6.The biofuel of claim 5 wherein the cetane additive is selected from thegroup consisting of substituted or unsubstituted, linear, branched ormixed linear or branched, alkyl or cycloalkyl nitrates having up toabout 10 carbon atoms, and mixtures thereof.
 7. The biofuel of claim 5wherein the cetane additive is selected from the group consisting ofdialkyl peroxides of the formula R1OOR2 wherein R1 and R2 are the sameor different alkyl groups having 1 to about 10 carbon atoms, andmixtures thereof.
 8. The biofuel of claim 5 wherein the cetane additiveis selected from the group consisting of 2-ethylhexyl nitrate,di-tertiary-butyl peroxide and mixtures thereof.
 9. The biofuel of claim1 wherein the hydroxyl-containing organic compound includes at least onemember selected from the group consisting of C1 to C4 straight andbranched chain monoalcohols, C2 to C4 mono- and poly-alkylene glycols,derivatives of C2 to C4 mono- and poly-alkylene glycols provided thatthe molecular weights of such polyalkylene glycols are suitable for usein the fuel compositions, and mixtures thereof.
 10. The biofuel of claim9 wherein the alcohol is selected from the group consisting of ethyleneglycol, diethylene glycol, triethylene glycol, propylene glycol,dipropylene glycol, tripropylene glycol, and mixtures thereof.
 11. Thebiofuel of claim 1 further comprising a supplementary low viscosity, lowdensity combustible liquid selected from the group consisting ofhydrocarbon solvents, paint thinner, turpentine, mineral spirits andmixtures thereof.
 12. A method of preparing an emulsified fuelcomposition comprising: (A) providing the following components in theamounts based on the total weight of the composition: (1) about 50 wt %to about 95 wt % of at least one liquid oil of vegetable or animalorigin or mixtures thereof; (2) water in an amount sufficient to producea water-containing dispersed phase comprising about 1 wt % to about 50wt % of water; (3) about 1 wt % to about 25 wt % of ahydroxyl-containing organic compound selected from the group consistingof monohydric, dihydric, trihydric and polyhydric alcohols, providedthat when a monohydric alcohol is present there is also present at leastone of tert-butyl alcohol, at least one C2-C4 alkylene glycol or amixture of both; and (4) about 0.05 wt % to about 10 wt % of at leastone emulsifier; (B) mixing components (A)(1)-(A)(4) with one anotherunder conditions of high shear, thus producing a dispersed phasecomprising water-containing droplets having an average particle size ofless than about 20 microns.
 13. The method of claim 12 wherein saiddispersed phase comprises water-containing droplets having an averageparticle size of about 0.1 to about 10 microns.
 14. The method of claim13 wherein the at least one emulsifier exhibits a hydrophilic-lipophilicbalance, HLB, of about 8.5 to about
 18. 15. The method of claim 14wherein the at least one emulsifier is selected from the groupconsisting of polyethylene glycol-polypropylene glycol block copolymers,sorbitan monooleate, sorbitan monostearate, sorbitan monopalmitate,sorbitan monolaurate, polyoxyethylene (20) sorbitan trioleate,polyethylene (20) sorbitan monooleate, polyethylene (20) sorbitanmonolaurate, and mixtures thereof.
 16. The method of claim 13 includingfurther providing an effective amount of an additive to increase thecetane number of the biofuel composition.
 17. The method of claim 14wherein the cetane additive is selected from the group consisting ofperoxides, nitrates, nitrites, nitrocarbamates, and mixtures thereof.18. The method of claim 12 wherein the hydroxyl-containing organiccompound includes at least one member selected from the group consistingof C1 to C4 straight and branched chain monoalcohols, C2 to C4 mono- andpoly-alkylene glycols, derivatives of C2 to C4 mono- and poly-alkyleneglycols provided that the molecular weights of such polyalkylene glycolsare suitable for use in the fuel compositions, and mixtures thereof. 19.The method of claim 12 wherein the components are provided and mixedsubstantially simultaneously.
 20. The method of claim 16 wherein thewater is premixed with the components other than the vegetable oil toproduce an aqueous mixture and the aqueous mixture is thereafter mixedwith the vegetable oil.
 21. The method of claim 13 using high sheargenerating mixing equipment.
 22. The method of claim 21 wherein highshear is generated using mixing equipment capable of generating andintroducing ultrasonic energy into the mixture.
 23. The method of claim22 wherein the amount of emulsifier is from about 20% to about 90% ofthe amount emulsifier required to obtain the dispersed particle size inthe absence of the use of ultrasonic energy.
 24. Emulsified fuelaccording to claim 1 wherein the average droplet particle size isselected from the group consisting of about 0.01 to about 15 microns;0.1 to about 10 microns; 0.5 to about 5 microns, and mixtures thereof.25. Emulsified fuel according to claim 24 further comprising aneffective amount of an additive to increase the cetane number of thebiofuel composition.
 26. Emulsified fuel according to claim 25 whereinthe cetane additive is selected from the group consisting of peroxides,nitrates, nitrites, nitrocarbamates, and mixtures thereof. 27.Emulsified fuel according to claim 1 further comprising at least onemember selected from the group consisting of thermal stabilizers, agingstabilizers, antioxidants, coloring agents, dyes, markers, odormodifying agents, rust inhibitors, inhibitors of gum formation, metaldeactivators, upper cylinder lubricants, friction modifiers, detergents,bacteriostatic agents, fungicides, microbiocides and mixtures thereof.28. The emulsified fuel according to claim 25 wherein the emulsifier isselected from the group consisting of polyethylene glycol-polypropyleneglycol block copolymers, sorbitan monooleate, sorbitan monostearate,sorbitan monopalmitate, sorbitan monolaurate, polyoxyethylene (20)sorbitan trioleate, polyethylene (20) sorbitan monooleate, polyethylene(20) sorbitan monolaurate, and mixtures thereof and wherein the alcoholis selected from the group consisting of ethylene glycol, diethyleneglycol, triethylene glycol, propylene glycol, dipropylene glycol,tripropylene glycol, and mixtures thereof.
 29. The emulsified fuelaccording to claim 28, further comprising a supplementary low viscosity,low density combustible liquid selected from the group consisting ofhydrocarbon solvents, paint thinner, turpentine, mineral spirits andmixtures thereof.
 30. The biofuel composition of claim 1 comprising oilobtained from the seeds or fruits of plants or mixtures thereof.
 31. Themethod of claim 12 comprising oil obtained from the seeds or fruit ofplants or mixtures thereof.
 32. The biofuel of claim 2 wherein the atleast one emulsifier comprises a mixture of at least two emulsifierswherein at least one of the two emulsifiers exhibits a low HLB value ofabout 1 to about 6 and at least one of the two emulsifiers exhibits ahigh HLB value of about 6 to about 20, provided that the low HLB valueand the high HLB value are not both equal to
 6. 33. The biofuel of claim32 wherein: (I) the sum of (a) the weight of water and (b) the weight ofhydroxyl-containing organic compound; divided by (II) the weight ofvegetable and animal fat and oil is lower than about 0.25.
 34. Themethod of claim 14 wherein the at least one emulsifier comprises amixture of at least two emulsifiers wherein at least one of the twoemulsifiers exhibits a low HLB value of about 1 to about 6 and at leastone of the two emulsifiers exhibits a high HLB value of about 6 to about20, provided that the low HLB value and the high HLB value are not bothequal to
 6. 35. The method of claim 34 wherein: (I) the sum of (a) theweight of water and (b) the weight of hydroxyl-containing organiccompound; divided by (II) the weight of vegetable and animal fat and oilis equal to or less than about 0.25.
 36. An emulsified fuel mixtureprepared from the following components: (A) 1500 parts vegetable oranimal oil or fat; and (B) 900 parts water; and (C) 400 parts denaturedethanol 90 wt % (180 proof); (D) 30 parts of at least one componentselected from the group consisting of (1) hydrogenated castor oil; (2)cetyl alcohol; and (3) a mixture of (1) and (2); and optionally furthercomprising 500 parts of a supplementary combustible liquid.
 37. A methodfor preparing an emulsified fuel mixture comprising: (I) mixing (A) 400parts denatured, water-containing ethanol 90 wt % (180 proof); and, (B)30 parts of at least one component selected from the group consisting of(1) hydrogenated castor oil; (2) cetyl alcohol; and (3) a mixture of (1)and (2) to form an additive; (II) mixing the additive with component (B)900 parts water, to form a mixture (II); (III) adding mixture (II) withconcurrent mixing to (D) 1500 parts vegetable or animal oil or fat toproduce a substantially emulsified mixture.